I have returns top and bottom in the rooms with the high ceilings. I used to switch them around for summer or winter, until I almost fell off of a ladder one day trying to reach one of the upper ones. It is about 14 feet high.
I mentioned this to Beenthere and he suggested leaving it open, so I tried this by always leaving the top open but adjusting the bottom. Now all returns are wide open and performance in every room on every floor is so much better. I could have really used this last winter.