Where to start with treatment?

[Byra]

Hi,

I'm basically done with the construction of my one room studio/rehearsal space. All that's left is hanging my doors, which will happen in a couple of weeks when they are delivered. The room is 25.5 feet x 15.5 feet, with a vaulted ceiling running the length of it. The peak is 10 feet and the side walls are 8 feet. Ive attached a picture for reference.

My question is what should I do as a first pass for acoustic treatment? Ive got 48 peices of 4lb 4" thick rockwool.

My current plan is to:
1) build about 15-20 broadband absorbers (1 piece of rockwool each) and hang them on the walls.
2) build superchunks in 3 of the corners. One corner has the minibar, so I cant put a chunk there.
3) hang more broadband traps under the vaulted ceiling peak.

However, Ive been reading about poly-cylindrical diffusers and they seem useful. I like the idea of bass absorbtion and higher frequency diffusion all in one. I'm now considering replacing a few of the absorbers with polys, and maybe use them to cover the vault peak as well. And maybe also using them in the corners instead of superchunks.

I realize that doing room testing is the proper way to do this, and I will do that, but I want to do something as a first pass and then refine it according to test results. I do know that there is a nasty mode right around 63 Hz in the room, but its empty and all surfaces are reflective. Eventually there will be a rug or two, a couch or two, furniture, etc.

Thanks for any and all advice, and feel free to let me know if Ive left out important info or goals.

--Byra