Go to Keeneland race track in lexington

There is an outlet mall at Edinburgh, Indiana on I-65.

In Louisville, you can drive out Preston Street to the Okolona area and have Bootleg Barbecue in a former gas station. That's pretty much a USA experience (and the food is delicious).

If you go to Lexington, you can go by way of Harrodsburg and see Fort Harrod and then tour and have a good lunch at Pleasant Hill Shaker Village. On the drive on into Lexington, you will drive through beautiful scenery past horse farms. The road is a designated scenic highway.

There are no bad seats at Slugger Field really. Maybe avoid the first base side at an afternoon game - so you won't be facing into the sun. It is a great place to watch a ball game.

The Eiteljorg museum of the American Indian in Indianapolis, Indiana is worth seeing. There are artifacts from Eastern Woodland, Plains, Southwest and Pacific Northwest Amerindian cultures, as well as westen paintings.
Maker's Mark in Loretto, Kentucky is a small distillery making fine sour mash whiskey. They offered a very good tour when I was last there. You might check their web site to see if it is still done. If you want to buy whiskey, it may not be available there. Unless the voters have changed their minds, Maker's Mark distills whiskey in a county where it cannot legally be sold.
Berea, Kentucky is a small college town known for high quality arts and crafts. Back when the Appalachains were a place that offered little opportunity to its people, the college taught arts and crafts to the local young folks. That tradition remains today. If you don't have time to see the town, there is an artisan center worth visiting right off Interstate highway 75.

Correction!
I checked, and one can now dip the neck of his own Maker's Mark bottle in wax and purchase it at the distillery, although it may be more expensive there than at a package liquor store.

You won't see much "real America" if you are using the interstate system.

What routes are you planning on taking through Indiana to Louisville? Keeping in mind that it would take you at least 8 hours of pure driving time to get through the Hoosier state (Indiana), are you planning on going any further south than Louisville?

I'm only going to comment on the Indiana drive since I'm not sure what your anticipated route, ages and interests are. The very topmost portion of NW Indiana is highly industrial until you get east of Portage, IN or south of U.S. 30. So, IMHO, I personally wouldn't be spending too much time getting through that area.

The Indiana Dunes National Lakeshore and Indiana Dunes State Park would be a very good option for you, if you were interested in nature and going eastwards.

Going south, after reaching U.S. 30, you would be traveling through very flat farmland for many miles - until Indianapolis and somewhat beyond, although you'll find it getting hillier the further you go south.

Of course, if you are racing enthusiasts, you probably would want to visit the Indianapolis Motor Speedway Museum while you are passing through the area. BTW, Indianapolis is the 12th largest city in the U.S. so I'm sure you'll find plenty to do, if you stop there.

So, here are a few options for you from Lafayette to past Indianapolis:

If you look at a map, you will see U.S. 41, which travels N/S pretty much parallel to the Indiana/Illinois border. U.S. 41 travels past the Turkey Run State Park and through Parke County, which has a very large concentration of covered bridges. You can pick up maps of where they are located in Rockville, although I believe there are some maps online.

Hint: You can rent canoes to paddle on Sugar Creek, if you wish.

Some other areas in which I think you might have interest are south of Indianapolis about an hour's drive away. To the southwest is Bloomington, Indiana (home of Indiana University) and, (look at the map now), traveling on SR 46 eastwards, you can travel to Columbus, IN. You would be going through Brown County, which is a lovely area of the state. Beanblossom is a mecca for bluegrass music. Nashville has an artist colony, small shops, B&Bs (and if you wanted to stay in a log cabin you could do that, too.)

From that area, you could drive south through one section of the Hoosier National Forest (looking at your map, you'll see that there are four sections to it) to Salem, maybe go to French Lick, if you wish. Beautiful driving in this area. You'll pass through the tiny little town of Story, IN along the way, where you might wish to dine. Also, east of Salem is Vincennes, Indiana's first capital.

As you can see, you aren't that far from Louisville at that point. You might even desire to visit Corydon while passing through - which was Indiana's second state capital.

Or, perhaps, you'd like to go to Madison, IN and Clifty Falls State Park. They are to the southeast of Columbus.

Whatever you decide, if you are looking at the small town experience, you'd be better serviced by staying away from the interstate system of driving. That's for expediency's sake.

Here are some websites for you to review:
www.nps.gov/indu/index.htm
www.turkeyrunstatepark.com
www.coveredbridges.com
visitindy.com
www.indianapolismotorspeedway.com
www.visitbloomington.com
www.browncounty.com
www.columbus.in.us
www.beanblossom.us
cityofsalemin.com
vincennes.org
www.frenchlick.com
visitmadison.org
www.in.gov/dnr/parklake/inns/clifty (hyperlink on this page for the state park)
www.thisisindiana.org/content.asp

P.S. I would assume that you are traveling over a weekend. If so, do take advantage of the local farmer's markets in the various areas. As a matter of fact, once you've decided on a route, take a look at the local area's newspapers on-line - once you get closer to your visit. You could go to a local fish fry, pancake and sausage breakfast or another civic event in one of these small(er) communities.

After proofreading this thing three times, I just saw an error right after posting! I meant further south of Lexington, KY, not Louisville, KY. Sorry.

Thanks so much to those of you who replied. All the advice + suggestions are wonderful! Our road maps for Indiana and Kentucky have arrived today . We will certainly stay off the Interstates as much as possible. We are looking at visiting as many of places that you have listed as possible - covered bridges, Beanblossom, Pleasent Hill ,a Whiskey Distillery, a scenic drive from Mt Vernon or Eavnsville to Louisville and maybe then onto Aurora. The BBQ + Fish Fry suggestions sound fantastic, we will definitely try them. We are going to book tickets for a game at Slugger's Field too.
Any advice on what we could see + do South and West of Louisville.
We will have hours of pleasure just planing our trip.

Bardstown, KY, is a neat little town. It has My Old Kentucky Home to tour and Talbott Tavern in which to eat. TT is a very old inn. St. Joseph's Cathedral is there. It has huge columns inside that look like marble but are actually painted tree trunks. Kurtz Restaurant is across the road from My Old KY Home. They specialize in southern cooking and have delicious fried chicken livers with biscuits and gravy and melt-in-your-mouth cream pies.

Mammoth Cave National Park is ~100 miles south of Louisville on I-65, and the Corvette Museum is on down I-65 near Bowling Green.

If you want to have fun at slugger field get seats in left field as the sun won't be in your eyes and you might have a chance of catching a foul ball. Thursday home games have a happy hour starting at 5pm and Friday night games usually have fireworks. The Louisville bats are a minor league team so the atmosphere is not going to be the same as you would experience at The Great American Ball Park in Cincinnati with the Reds....which would also be an option for you.

Suggestions for Louisville:
Close enough to walk from a Bats game is a Blues Bar called Stevie Rays.
http://www.stevieraysbluesbar.com/

Waterfront Park in front of the Stadium is great for walking and depending on when you are in town they have a free concert on the last Wednesday of each month. Just Bring a lawn chair or blanket to sit on and enjoy.
http://www.wfpk.org/waterfront-wednesday-may-2012/

If you are hungry there is a small restaurant called Against the Grain Smokehouse and Brewery that is in front of the Stadium that has good food.
http://www.atgbrewery.com/

4th Street Live is also an option.
http://www.4thstlive.com/

The Highlands is a neighborhood in Louisville you might enjoy visiting. Sunday nights they have a free concert series in Cherokee Triangle...next to Cherokee Park.
http://www.louisvilleky.gov/metroparks/parks/cherokee/

http://www.kentuckytourism.com/events/events.aspx

Kentucky Train Museum is not far from Lexington

While in Kentucky, have a Kentucky Hot Brown for a decadent dining experience. Toast topped with turkey meat, smothered in mornay sauce, crispy bacon on top, maybe some tomato slices? and run under the broiler so the whole thing is bubbling and brown on top. So rich but so good. After two 10 day trips to Louisville for work, the best one I found was from room service at the Galt House Hotel. There is something wonderfully naughty about eating such a cheesy plate of deliciousness alone in your hotel room, but I think the main restaurant probably serves it too if you want to eat it in public (you will have to hold down your moans of pleasure, though!).

I really enjoy walking or jogging down Main St from 4th to the Louisville Slugger museum and back- in the early summer when I go, the public flower plantings all around this area are stunning and there is lots of interesting public art scattered around. The area around the courthouse has a lovely garden for a quick stroll and benches for a take out lunch. The walk along the river is nice and I love seeing the paddlewheel steam boat docked by the Galt House, even though I am at work all day and can't take a ride.

The home of the Hot Brown is the historic Brown Hotel at Fourth and Broadway. I agree--delicious!

Also in Louisville, the Speed Museum (Art not cars!) which is lovely. Churchill Downs racetrack has a very interesting museum if you would like to know more about racing's U.S. history in comparison to the sport of kings. The Kentucky Horse Park (http://kyhorsepark.com/) is very interesting-more horse history and a very nice gift shop if I recall correctly.

I second one of the distilleries, Berea and Shaker Village as well. The Brown and the Seelbach were the grand old hotels when my hub was younger. There is a nice arts center in the downtown area.

There are some lovely horse farms between Lville and Lexington. Can someone mention the route number to see them? 60?

Yes, U.S. 60 goes to Lexington from Louisville.

Some already mentioned I think.. but my quick list:

Cumberland Falls.. very nice park
Berea, Kentucky
Southern Indiana..

you will find fun casinos along the river

Look for amish towns .. most are in northern indiana, but googling you can find them almost anywhere.

Check out local small town museums. Sometimes they have local crafts for sale at a good price.

Columbus, Indiana, as mentioned, for architecture by world renown architects. Has as much interesting architecture as any large city, but very easy to visit.

If you like Golf, go to golfdigest.com to find 4*courses at 1* prices.

Abraham Lincoln's home

Metamora (not far from Columbus, Indiana), miniscule town with donkey/horse pulled barges along small canal

Cincinnati Ohio.

www.hotwire.com and bidding www.priceine.com will provide you with less expensive lodgings. see how they work at www.betterbidding.com

here's a bit on Metamora.

http://www.metamoraindiana.com/index.htm

amish gateway southern indiana

http://gasthofamishvillage.com/

If you're going to do to any bourbon, you must hit Bardstown - the world's bourbon capital...a great little southern town with lots of things to do and wonderful restaurants. www.bardstowntourism.com