try the cardas homepage for an excellent short piece on speaker placement in the 2 ch world. i'd not even try to mix a 2 ch with 5ch in the same room. you cannot hope to get optimal 2 ch sound when you've got video stuff between your 2 ch ("main") speaks. perhaps, in your case, the "best" placement is whatever your wife accepts!
Optimum speaker placement
I am about to go to war with my wife and set up the 2ch/5.1ch in the den as optimally as possible. Before I bring it to her (and the negotiations begin), I need to know what constitutes the "ideal" placement arrangement. I know that mathmatical formulas have been around for years, however I haven't any clue what they are. Additionally, room treatments will play a significant role. Does anyone know of any printed material (or web-based) that I can review? Thanks in advance for your advice. - Ken