Actually, we just had a member here a week or so ago that had a small studio and some of the same positional problems you're experiencing. I think you would find it interesting to read
this thread completely through. Positioning ended up being the best fix. I know it's a bit more difficult when it's a studio, but sometimes it's needed.
I think unlike a home theater where there are concerns for listening positions of other individuals, wouldn't a studio attempt to have a single sweet spot for mixing?
brucek