I'm ready to run speaker wire and would like some input on how high to mount the boxes in the walls (the room is unfinished). My room is 14' wide x 26' long and the screen will be mounted permanently on the wall. I'm not sure on the height for the LR for the fronts as well as the surrounds in the back (I'm wiring for 7.1). The side surrounds will go as high as I can get them - about 4' off the ground due to the ceiling slant - I'm in the attic. The sub will be in the corner next to the screen and I'm going with a bookshelf system, leaning toward the AV123 x-series. I'd like to have the speaker wire boxes mounted close to the height I'm going to have the speakers.
Thanks.

I was just wondering the same thing. What I read is that the rule of thumb is that the speaker height on the sides and rears should be at your ears if you're standing up. Since I'm only 5-8 and you might be 6-8, there is obviously some wiggle room in this theory.

From what I've also read, the rule of thumb for the front speakers is to have all three L/C/R at the mid-screen point. For those of us who aren't going with acoustic transparent screens, the dilemma is whether to put the center higher or lower than the screen.

Hopefully somebody smarter will come along and point you (us) in the right direction if my so-called "rules of thumb" are "rules of dumb"

I plan on blocking between the studs where my sides and rears are going to go so I can play with height a little bit.

I think ear height when seated or higher is best for the front speakers. Mid screen should be fine too. If you don't have an AT screen, then it's better to put the center above the screen.

In my situation, I have an arched soffit that we built above where the screen will go.

Will it be better sound to have the speaker directly above the screen or above the screen but hide it in the soffit so it would be a couple of feet in front of the screen?

I think in the soffit looks better. You just have to calibrate a delay into the center speaker setup since it will be closer than the left and right. Just about every audio precessors will do this in the speaker setup.

I have sloped ceilings, at each end and on the sides due to the ceiling following the slope of the roof. I will be mounting my center channel underneath the screen, and the other two fronts to the left and right of the screen, about 3' off the ground.
The side surrounds will be about 4' off the ground due to the ceiling slant, I can't go any higher unless I move them toward the center of the room and I don't want to do that. The back speakers will be a little under 6' from the floor, mounted on a wall. This may not be 'optimal' but I think this is the best I'll get for the time being. I can play around with a little when I get my system. Thanks for all the input.