We usually try and do both each trip, and we always have a pleasant experience in Sci Fi, we have had good times at 50's and not so good times. If we were forced to choose one over the other, I think we would pick Sci Fi for most of the reasons people already mentioned....50's does tend to get loud, we don't feel like we get very good service in 50's, the waiters are sometimes too busy goofing around to really take care of our needs, we
ALWAYS have to wait a long time at 50's and we always have PS, we have been able to walk in to Sci Fi several times and get a table without PS with a reasonable wait, that would never happen at 50's, but we really like the food at 50's, it's basic fare and more reasonably priced, we spend a lot more money at Sci Fi, the food selection gets pricey if you like the fish & steak on the menu and we always order drinks in Sci Fi which adds up our bill, at 50's we stick to milkshakes, sodas & ice tea. So it really depends on your mood, the personality of your family, how much time you want to spend eating and what you're hungry for. My kids order the same kids meal at both places, so they don't care where they eat, but there's something about sitting in the front seat of that car in Sci Fi, they get a big kick out of that every time. They think they are the drivers I guess.