HELP - Building stereo room, need advice ASAP

I am building a new house with a dedicated stereo room which will be built to IsoRoom standards with ASC room treatments, the room was originally to be built to be 9x14.5x23.3 feet (golden ratio). Based on some design constraints, that will not happen :(

My other options are the following and I need advice to settle on the preferred alternative room size. My preference I think would be # 2 below, please advise ASAP. Whether it matters, my speakers are Revel Studio2's (the small brother of the Salons).

1) 8 x 12.9 x 20.7 ft (golden ratio)
2) 9 x 14.75 x 20 ft
3) 8 x 14.75 x 20 ft
Seems like you already have things well in hand with your stated standard and room treatments. Building the larger space, option two would allow for future speaker changes and add to the airiness of the room if nothing else. You have before you a great opportunity, live the the dream!
#2 and put panels on the ceiling. 8 foot is low
#2 biggest room volume you can manage. keep speakers well away from walls and listen quasi nearfield.

all rooms sizes as above will be fine. Do not forget about dedicated line(s) to your new listening room.

Happy Listening!
I'd go # 2 . size and volume are beneficial and allow more flexibilty. Hands down.
use min 5/8 drywall and minimum double on wall behind speakers
I have actually used both #1 and #3, and I strongly prefer the wider room (my present house). The narrower width caused more extreme nodes along the center axis resulting in a suckout in the upper bass/lowerr midrange region. The wider room is more neutral.

It's quite possible the same L x W dimensions with a 9' ceiling would be even better. I need to figure out how to raise my ceiling.
Right now, this second, go out and beg, borrow, buy, or steal a book on the subject.

I recommend The Master Handbook of Acoustics by:F. Alton Everest & Ken C. Pohlmann

I read it before during and after the construction of my room. And I believe the results speak for themselves. All the above methods and idea's mentioned above are very good. But a reference guide can be worth more than just money.

Synesthesia Studios