Speaker Placement

OK, guys- I've spent several hours combing through theories, threads and treatises and am still at ground zero to determine initial speaker placement. Got a a pair of Maggie 12's with a powered sub going into a 16 1/2 by 22 1/2 room. The ceiling is coffered from 8 feet at the walls to 10 feet. (slope is 6 in 12) Floor is carpeted, walls and ceiling are sheetrock.

So far, I've heard it all- close to the wall, far from the wall, close to the side walls, further from the side walls, sit closer, sit farther etc, etc, etc.

Any planar placement formulas/experience out there that will get me started?

Thanks
Jim