Enjoy great views of the North side of the city while enjoying cocktails at the Signature Lounge (96 floors up).

Also, check out the thread about Chicago's best burger in the Chicago forum.

If you can afford it (or if you're lucky and get the right rate), then I'd recommend either The Drake (just off Michigan Avenue) or The Intercontinental (on The Magnificent Mile).

Enjoy a long walk northwards along the lake front, starting at Navy Pier.

Oh, and I can't believe I forgot to visit the Art Institute (home of the painting featured at the start of Desperate Housewives).