My contractor/electricians put my sconces too high and it looks so bad. By the time they told me about the installation the wiring was all done and not enough slack was left. My boxes are at about 70" now after I brought them in and down a little. Maybe that's OK for a downward facing sconce, but mine are fairly rectangular and mount flush to the wall. I would say 66" would be pretty good. The point of bathroom sconces is to light the sides of your face. For a guy it's great so you can see under your chin to shave. The tall sconces make my bathroom look like it's off scale.

Up with the arm so of course I pick up the phone ;-) that's what I get for roller blading with my children after 30 yrs! It's funny how addictive decorating can be, I love seeing my visions come to life.

I agree with the commenters here. Your placement looks good. It is ideal to have it put up for your (or an average of your family members) height, around eye level. You do not want to catch a glare from the bare bulb when standing at the mirror, and you want it at the correct height to cast as much light as possible on your face. Side lighting does wonders for bathrooms & mirror areas. If you put the fourth sconce up, make sure to look at a "mock-up" of it on the wall first. It might be tight when you put two sconces between those mirrors. (although 2 sconces per mirror is ideal for balance/proportion/light if you have the room) But I also agree with the other advice from the pros above. Get as much light as possible out of them. Use the highest wattage bulb and shades that let a lot of light through. Play around with the color temperature of the bulb as well. The light cast by the bulb will interact with the other colors of the room, but overall a warmer color temperature usually makes us look better in the mirror.

Depends on where you are putting lighting I happen to like vanity lighting above the mirror