Sober, huh? While some of these places may be more *meh* while the sun is out or while sober, they are amazing after a night out. Of course it depends where you are, as the last thing you want to do late-night is drive around a lot.
LTH - Duh! In fact, I don't think I've ever been here in the daytime. And many restaurants in Chinatown are open late, so you have options.
Hae Woon Dae - Korean, great anytime
Lincoln Park Pizza - a good slice
Suzie's - A gut buster, but cheese fries in a taco salad shell is a revelation after a few. The "Phillys" are also pretty good, if not at all authentic
I'm sure there are many more, but these are the ones I go to most often.
mike
Stickin' together is what good waffles do!