I am very surprised at the responses that say Pecos Bill's burgers are good. I have tried them a few times and always thought they were pretty bad. Dry buns and over cooked, dry meat. The "fixins bar" doesn't help make it that much better. But if you do decide to eat there, look for the room that looks like an outdoor courtyard. That is my favorite room to eat a mediocre burger in!
I thought the burger at Sci Fi Dine In was good, but that is not QS.