If you're a builder/general contractor, and not a design specialist, I recommend getting someone with an interior design or interior architecture degree and at least 5 years of experience to do that aspect of the job. Even better if you can find one who's already done a few high-end home theaters. Hell, an Architect with home theater design experience might even do. You've got several things to consider including:

Acoustics and soundproofing design
lighting, and light level control
remote control/automation,
equipment specification
speaker, lighting, A/V signal, and popcorn machine wiring

and so on.

Good luck with the project. Sounds like fun.

Dave B.