With 21x22, 2 big rectangles? Or go with the SAE design?

I have 21x22. The floor is over the garage, brand new, suspended on I-joists with a 9 foot flat ceiling. I'd like to leave about a 3 foot walkway where the garage meets house, so if I make two rooms they will be approx 10-11 feet wide and 17-18 feet deep. Am I better off trying to get a control room and live room out of it rectangularly, or going with something like the SAE design and splaying walls but having little tiny rooms? I wish I could find some actual pictures of studios people have done using the standard corner control room SAE example. Seems like it would be very small. 10x18 already seems small (narrow) enough. Also, if I use 2 rectangles... the width and length will depend on where I put the rear wall, and how much space I leave between the double walls seperating the rooms. Is there a "best" size that I can make the rooms with the amount of space listed? I mean like going with 10 feet wide but 17 deep so that its not 2 even dividable numbers? If I only had another 5 feet in both directions I would feel so much better. Sigh. All words of wisdom appreciated. Oh! The wall where the mix posi would be is already drywalled. I intend to frame up a steel stud wall directly against it, pack it with 4 inches of rockwool, and cover it with a very nice looking fabric. Also the wall to ceiling and wall meets wall area behind the mix posi are going to be bass trapped with 4 inches of rockwool, in a verticle pattern rather than horizontal (i.e. more space behind the traps) The area directly above the mix posi will have a 4 inch cloud of rockwool about 4 inches off the ceiling, and the early reflections will be killed with 2 inch rockwool panels. Bass traps will extend the entire length of the room if you think I should, and maybe even where floor meets wall about 6 feet out from the mix posi wall. Does that help any?

Darn.