Speaker placement for the rear HT

Thiel CS 2.3s up front, small moniters for the rear in a 5.1 channel HT system. Some people place speakers mounted from ceiling, some from side or rear walls. I know every room is different. Any consensus on most rear HT speakers
Put them where they sound best to you,after all,you will be the one listening to them.Just a thought.
ceiling is fine, they fire so seldom it really doesn't make much of a difference. If you play surround SACD's or DVD-audio, then it can make a difference, but for HT, some ceiling speakers are fine.
How big is your room? And are the rear surrounds bipolar, dipolar or monopole? Thats an important factor.