I'd go with free-standing, on-walls, or in-walls for the front and center speakers.
Pick a budget, sky is the limit.
Here is a nice speaker for you, $100K each.
http://www.audiogon.com/cgi-bin/cls.pl?spkrfull&1297225466&/N-B-S-Butter/Fly-ful-range-spe
Only slightly used.
Oh, do you have a budget?
I've been pretty happy with Proficient in-ceilings. Nothing special, but solid, well made, and won't break the bank.
I use Proficient for some of my distributed audio zones.
I will get something more expensive then Proficient when I upgrade my LCR speakers. But, it will depend a lot on what I am willing to spend, at that time.
You may want to talk to some local installers, that have demonstration space available.
I would splurge on the LCR, and get much cheaper on the rears.