Those 12' ceilings are a great, great asset.
"Everything keys off the ceiling height." https://www.decware.com/paper36.htm
Amroc: you're in the "bolt area" -- https://amcoustics.com/tools/amroc?l=19.75&w=17.5&h=12&ft=true&r60=0.6
Read about this, but basically it means that you won't have the worst room modes.
I strongly suspect that you don't need to do anything with your ceiling because they're high enough to avoid terrible first reflections.