i have a centre above the tv, floorstanders for fronts, rears are about 7 feet up, side effects are 2 smaller denons, still not 100% how to mount them so for now 1 is on the mantel, 1 is on the rad ... all running off a denon av receiver, speaker cable from richer sounds, about £1 per metre.
i looked at putting the rear speakers lower but it looked odd & 1 of them would have probably got knocked around.
i decided i wanted a good surround set up but still wanted a front room that was practical.