I can't do "hammer height" because I almost never use a hammer!
Due to ADA, etc., I've gotten in the habit of placing the bottom of my box at 18" above the unfinished floor- or, alternatively, matching the location of existing receptacles.
I tend to place my switches at 48" from box bottom to floor. This is a little higher than many, but the sheetrock guy only has to make one cut in each piece of rock (receptacle in bottom piece, switch in top piece.)
Data/Phone at same height as receptacles.
Thermostat at 60", box CENTER to floor.
Other spacings:
Try to place switches at least 6" from rough door opening, to allow for molding, etc.
Try to place receptacles so that they will be next to, not behind, furniture.
Also try to anticipate door swing, so door doesn't block.
