[bpape]

You're right. Both have plusses and minuses. The windows themselves are an easy fix acoustically but the isolation issue sounds like a real problem.

Normally, I'd say work with the larger room but in this case it sounds like it may not be an option. The smaller, more square room will present more challenges but at least it is quiet (relatively) to start with.

As much as it pains me, I think I'd have to go with the smaller room and deal with the internal issues. With your budget, there is a lot that can be done to deal with them regardless of which treatment option you choose. You'll have to pay careful attention to seating placement and do a lot of tweaking of monitor position - but hey, those things are free. In a square room they're critical though.

Bryan