If you're downtown, Sammy's is THE place to hang out. Grab a beer (lots of drink specials), try some of their chili (which is great), or my favorite appetizer - Bosco Sticks.
The staff is friendly - and if you go there the wait staff will get to know you by name.
And.. if you're a sports fan... you're never far from a TV - they'll even adjust what's playing for you. A new addition are smaller tv's in the booths at the back of the place - very cool if you're like me and one of the only non-Bears fans in town.