Topsiders is always casual, making it a good alternative to the other dining rooms on formal and semi-formal nights. They have a decent basic dinner menu with nightly specials and a salad bar. My understanding is that you can ask for something on one of the other dining room menus (for that evening), since they all either share or have access to the same galley. I really liked Topsiders for dinner - unlike breakfast or lunch it was quiet, the food was tasty, and service was very attentive (even more so than in the dining rooms, if you can believe it - just don't expect any magic tricks or "excellent" service speeches). My only question is on tipping - the servers are not from the dining rooms and other than adding extra to the bar tab (which I don't believe goes to the servers) or leaving cash on the table I don't know how to take care of them.