I went to a business dinner on Monday night at Catch35 in Chicago (http://www.catch35.com). I pitched up in my suit and Swift folder with all my cycling stuff in a back-pack. They were great and put the bike in the bag room. The food was excellent as well.
Restaurants that like folders deserve to be recognised!
Consider them recommended if you are in Chicago and like seafood (they do a decent steak as well)!
Ate the other day at Cafe Bionda in Wicker Park (Chicago). They had no issues with me keeping my folded Giant Halfway in a corner near my table. Food was good, not great... but the service was excellent.