Same problem here. I have an extra 21" and an extra 37", both perfectly functional. I had an extra 42" and put it in my basement where only the kids play(seriously, haven't been in my basement in like 3 weeks).
Thinking about putting the two extras down next to the basement 42" for NCAA tournament stuff.
My 37" is still hanging on the wall immediately behind my new 46" in my bedroom because I have been too lazy to take it down and the new 46" covers 90% of it.