If you're married have your better half sign off on absolutely everything you are going to do beforehand. My mistake was getting her to sign off on this being my room alone to do with what I wanted. Thirty years later complaints were still coming in, fortunately only sporadically.
Plan room entrances and walkways carefully so as to not interfere with speaker placement. I messed up on this and now have to place speakers much closer to the walls than would be ideal, and had to avoid ported speakers due to the wall's proximity.
Another small issue is not to have a couch for your prime listening spot that has the crack between it's cushions exactly where you need to sit. That alone will provide a daily annoyance that can last you years on end.
Plan the rooms decor to go with your speakers, or vice versa. That helps on the marital front too.
You've gotten a lot of good suggestions on this thread so far.. Good luck with the construction.
Mike
