Without having any idea about the types of things you like, here are some suggestions within walking distance:

Milwaukee Public Museum (1/2 mile)
Milwaukee Public Market (1/2 mile)- at the entrance to the Third Ward, which has lots of shops and restaurants
Milwaukee Art Museum (1 mile)
Harley Davidson Museum (1 mile)

The Milwaukee Repertory Theater has three stages in the same building as the InterContinental, and their productions are usually exellent.

Not sure exactly where your hotel is. However, the Botanical Garden is a must see.

The hotel is DT at the corner of Kilbourn and Water, not near any botanical garden--not sure if you're referring to the Domes or Boerner.

Sounds good, is there a riverwalk area nearby? Also, any good restaurants nearby, which aren't extremely pricey? Is the area around the hotel pretty safe to walk around in the evening?

You will be in a GREAT area!! Probably one of the best in the city. There are a ton of wonderful restaurants and brewpubs nearby (be sure to try anything from New Glarus brewing if you're coming out-of-state - they only sell in WI! Spotted Cow is a tried and true favorite). Water Street Brewery, Rock Bottom and Bar Louie come to the top of my mind that are within walking distance. Also: Alterra Coffee and Usinger's sausage are great to visit if you're interested in that sort of thing.

If you're into beer, I highly recommend a tour at Lakefront Brewery, about a mile from your hotel. The Friday evening tour was so laidback and a lot of fun, but whenever you go would still be a blast. The Third Ward is a fun and trendy area to visit, Cathedral Square Park is a cute one to amble around in, and it's always beautiful to walk along the lake from Veteran's Park down to the Art Museum. Definitely recommend walking around the art museum area, and don't hesitate to go inside the lobby - it's free!

For three days you should be able to get by without a car. You'll be staying in the main downtown area, very safe for Milwaukee with lots of amenities nearby. Obviously keep your wits about you at night, but for the most part I wouldn't be terribly worried. Have fun

The riverwalk is about 1/2 block west of your hotel on Kilbourn.

The area is safe in the evening, lots of restaurants, bars, and theaters nearby.

Some restaurant ideas: Rumpus Room (you can't go wrong with a Bartalotta restaurant), Rudy's (Mexuican), China Gourmet, Thai Palace, Water St Brewery.