You are right, I've seen people comment on the indoor tables at Pizza Planet. They say there are tables upstairs in PP and it is usually less crowded and noisey than it is downstairs.
Pizza Planet does have tables inside, but we've never eaten at them - it's always been too crowded.
Also at the Studios is the ABC Commissary. Lots of indoor seating and especially great if you're caught there in a thunderstorm (which we have been more than once ).