I'm cutting and pasting this from my answer to an Ask Metafilter question, but here goes:

Restaurants:
Kuma's Corner
Publican
Purple Pig
Longman & Eagle
Owen & Engine

Mixologist bars:
Whistler
Sable
The Aviary

Mircobreweries:
Revolution

Good beer bars:
Hopleaf
Map Room

Hot dogs:
Hot Dougs
Franks n Dawgs
Bangers & Lace (also has great beer list)

Neighborhoods:
Logan Square
Bucktown/Wicker Park
Andersonville/Edgewater/Uptown

As far as biking goes, yeah the Lake Front Path is great, though can be pretty damn crowded on the north side on nice afternoons. A lot of Chicago is pretty bike-friendly. Google maps bike directions are usually pretty good, and there's a free Chicago Offline Bike Map app for iPhones that is great because it doesn't require a data connection. It doesn't, however, do routing; it's just a map.

ETA: The Chicago Architecture boat tour/cruise is awesome. I love when friends/family come into town so I have an excuse to do it.

Also, the museum campus (which houses the Field Museum (natural history), Shedd Aquarium, and Adler Planetarium) is right on that Lake Front Path. The Art Institute is just a few blocks in from the lake.