I suspect that the OP is looking for a "real" wine bar loosely in the vein of 'ino in New York, where the only available food is made via a toaster oven. Unfortunately, Chicago doesn't really have one, except for maybe Webster's, as some of the best mid-priced wine lists in the city (i.e., Telegraph) are attached to restaurants, or the self-styled wine bars (such as Blue Star) are so-so in terms of wine. I think your best bet would be Webster's Wine Bar, where no one will care if you take a table and drink only a bottle. Food is definitely second fiddle there.
Otherwise, I'd say that the wine bar at Lush West Town comes a close second. Select any bottle from the store, pay retail, and drink it at a table in their comfortable seating area. They do serve some food, but it's mostly cheese and sandwiches.
(The addresses for Lush and Webster's are provided upthread.)