Did you choose March for a particular reason? If not I would wait until at least May when the major attractions are open. The weather at the end of March could be very cold and wintry. Maid of the Mist, Cave of the Winds, Journey Behind the Falls, etc. will not be open. Also, you will want to stay in Canada, not the USA. The park on the US side is worth visiting but the best hotels, attractions and views are on the Canadian side.

Yes, we're using our groupon which is on the US side as it expires on April and we don't have the time to go in April.

I hope the weather holds out for you! What hotel are you staying at? How long will you be in Niagara Falls? Do you plan to cross the border to Canada at all? There are some nice wineries, restaurants and shops just down the road from Niagara Falls Ontario in Niagara on the Lake. You're going to find Niagara Falls USA pretty run down with not much to do. There is a decent outlet mall on the US side but most people going to Niagara Falls don't go there to shop. Old Fort Niagara is also on the US side. The Butterfly Conservatory should be open on the Canadian side.

Sorry - but you may very well run into a lot of snow at that time and many attractions won; be open. Also the US side is a depressed are and not really someplace you want to stay.

Definitely wait at least until May for decent weather and visit the Canadian side for best views and better hotels,

I believe that your Groupon will still have the value of what you paid for it after it expires, so you won't lose your investment. To me it would be worth it to lose the savings to experience Niagara Falls when the attractions are open and the weather is good.

I live near Niagara Falls and agree late March is not an ideal time to visit. While it probably won't snow it will most likely be cool/cold and maybe damp. On the plus side it sure won't be crowded. I like your directions, Route 15 is slow South of Williamsport, but new highway construction north of makes the rest of the trip a lot faster. Perhaps consider stopping at Letchworth Park, there is an entrance near the Mt. Morris exit off of Route 390. Otherwise beyond the Corning Glass museum not a lot to see on the Route.
I actually prefer the American side, more natural and more parks. I refer to the Canadian side like locals elsewhere refer to Times Square in NYC or Fisherman’s Wharf in San Francisco. Wax museums, Ripley’s believe it or Not, etc. Locals don’t go there unless for the casino, but there is a nice one on the American side now as well. Niagara Falls is a bit gritty, but the park areas near the Falls are nice.

There is a decent Comfort Inn on the American side walking distance to the Park and Goat Island to view the Falls. The Casino, Crowne Plaza, and Hampton Inn also have nice rooms, but are further from the Falls. Consider going to the Como on Pine in Niagara Falls for good Italian food and great atmosphere.

Dave you gave some good advice but please explain how the Como has great atmosphere? I was only there once 5 years ago and found the food was okay, the atmosphere made me feel like I was back in the 1980's.

The atmosphere of the Como is '60s Mafia... sit away from the windows with your back to the wall...

I’ve been going to the Como since I was a little kid in the 60’s so may be looking at it with rose colored glasses. I admit that since the remodel/expansion several years ago it lost its old school charm. They still have all of those pictures of the stars and boxers who came through in the old days hanging though.

Make sure you go over to Canadian side of Niagara Falls and follow the Nigara escarpment down to Nigara on the Lake.

Thank you all for the suggestions. Just checked and both of our passports are expired so no on the Canadian side - next time. We do like the outdoors so hopefully if the weather is not too bad, we can walk around goat island. We will be staying at the Red Coach Inn. I grew up in San Francisco and we also go to NY at least once a year. So a little quiet time and bond with nature wouldn't be too bad. We already have plans in May, June, and July and vacation hours are already spaced out for the rest of the year.

Dave S., thank you very much. I was thinking of stopping at the Corning Glass Museum... seems very interesting.

What is the weather IS bad? The fact that you are driving gives you flexibility. I suggest you at least consider going elsewhere in late March and try for Niagara again next year (in summer and on the much preferable Canadian side).

Groupon or not - there are countless options south of Baltimore that are a similar (or shorter) drive time that would much better in March - even for nature walks, relaxing, etc.

Just my thoughts.

If you do use the US 15 Route over the mountain rather than the I-80 tie to I-180 to get to Williamsport, you can stop someplace in South Williamsport for lunch. You will also be going past the Little League Baseball Hall of Fame as you come into South Williamsport.
At some point in Western New York you will be on US 20 or 20A.
I would avoid the New York State Thruway (I-90).