Basement Studio design

Good afternoon all! Long time reader, first time poster. Recently purchased a new-to-us home, and my wife has said "the basement is yours to do with as you please (within reason)." First thing I did was buy and read Rod's book, so I could better understand the concepts of isolation. Fantastic read! Then, rubbing my hands with glee, I took some measurements and started throwing things together in Sketchup. After some serious thought, I came up with what I consider to be a decent plan for having a small live room, a couple of iso booths (mainly for guitar amp and maybe a vocalist for guides) and a control room. I'll attach that to this post. I realize that my rooms are rectangular, and will treat with care. I plan to build a room that can accomodate a standard 4piece band. Although I have no clients at this time, the musical tastes in my area are like most- ranging from jazz to heavy metal, so I need to accomodate the loudest common denominator. :) I'd like to keep the two room + iso concept. I will have 24 tracks HD (or DAW), a headphone cue system, etc. My plan is to follow the double wall construction, and I would like to use the independant ceiling system if possible. However, as you'll see in my initial plan, the existing HVAC line pose a bit of a problem. I chose the end of the house that the main feed runs under the existing joists, and the offshoot lines are in between the joists. There is only a little bit of plumbing and natural gas line to contend with in that area, but they run between the joists as well. Any other part of the basement would involve a lot of re-running of gas and plumbing through the joists, and I'm hoping to avoid that. I've left a rec-room area beside the control room, added a bathroom beside the water heater/HVAC, and a storage room at the opposite end of the house with the cold storage area. In between the iso booths I've included a small storage closet for mics and cables. Control room is approx 12' wide, 14' long, 7'5" tall. Live room is approx 9' wide x 14'8' long, 7'5" tall. Iso booths are 3'6" wide, 5'5" long, 7'5" tall. So, basically, I'm looking for any input-good, bad, or meh- and if someone wishes to take a crack at a redesign, that would be good too. I'm looking at a budget of around $20,000. Construction will follow Rod's recommendations (standard 2x4 walls, 5'8" drywall, Green Glue, etc). Is it possible to run some kind of joist along the length of the HVAC in both rooms which would allow me to attach my second ceiling? IE. can I strap three 2x6 (or 2x8) together, fasten them to the side walls (on external window wall towards separating wall between two rooms)? Is there any way of reorganizing this that will allow all that I've shown, and accomodate the second ceiling design I've chosen? Thoughts fellow studio-philes? Your help is appreciated! Andy