I highly recommend the original Billy Goat Tavern if you come to Chicago or already live here. (the one below Michigan Avenue not at Navy Pier) It is famous from the SNL skit and a landmark in Chicago. I finally tried their famous horny goat drink tonight while watching the Cubs game. (Sprite, Bacardi limon, and cranberry juice) The decor is old and worn (even yellow from smoke)... but the staff is friendly and the burgers are great. (cash only)
Next up is berry chill, which is like pinkberry.