My thoughts are two of the same size round mirrors over the vanities and a bigger rectangle over the make-up spot.

This is becoming stressful..with the silver travertine flooring and off-white cabinets we have decided to go with stainless light fixtures...the dilemma is..

As you can see we have his and hers separate vanities, his being quite a bit smaller. How would it look if I mounted an over the mirror fixture on his and sconces on hers

Just two of the same size with the same lighting. The mirrors are above the sink, not so much above the width of the vanity. Hope that makes sense :)

And a large piece of mirror over the make-up part of your vanity, from counter up.

Or no large make-up mirror and a freestanding one with light in it:

Option too: huge mirrors with sconces in it? (maybe a bit too much mirror, right?)