Never been to 50's, but I love Sc-Fi, it's a must do for us. As far as the food goes, I have severe food allergies and have not very much to compare it too as far as other great foods go, but I really loved everything about it. I just get the burger, fries, and coke and everything is wonderful, the atmosphere, people, and food.
I hope to try 50's next time!
Disney is really the only place I can ever eat out because they are so accomidating. Other than that, I am stuck with the basic Subway, McDonalds, Pizza Hut, and that's about it! Oh and Home Cooked meals! Can't beat those!