All my friends tell me "you have to go to Serendipity" when you are in Vegas -- I did, for my 21st birthday lunch and I loved it. Its a really cute place, although the wait is kinda long, but I expected it so it didn't bug me much. Our waiter was extremely friendly -- he even offered to sing happy birthday. Two things that are a must get, the mac and cheese (OMG SO GOOD) and frozen hot chocolate!