Hi, I would decide first what you want to do for mirrors if you want one large mirror you could put a sconce at either side or you could put a light above each sink. if you have two mirrors one above each sink you could put up three sconces two on the Outer Edges and one in the center or still have a light above each mirror and then I would also put up a main ceiling light. The size of the lighting is really about personal taste because you can get very large sconces or smaller single light sconces but a double light will potentially give you a brighter space

Here are a few ideas

https://www.houzz.com/photos/camillia-contemporary-bathroom-los-angeles-phvw-vp~115700334

https://www.houzz.com/photos/blessings-golf-course-home-farmhouse-bathroom-phvw-vp~120315386

I doubt you have room for sconces. I would do a double light over each sink or a 4 or 5-light fixture in the center.

This looks like a custom vanity. I love a pretty vanity as much as the next person but this is not a good design with 19" sink bases. Will a standard-size sink fit in a 19" cabinet? You don't want a tiny bar-type sink for washing your face. Will a plumber fit in a 19" cabinet? 24" is standard, and with it being inset cabinetry, you're losing door width, as well as limiting access with a bottom drawer. You've worked so hard to create symmetry in this design that you've sacrificed functionality.

The problem with lamps directly over the sink is that they throw bad shadows. Most interior decorators we work with suggest lamps alongside the vanity, either ceiling mounted or sconces. Side lighting is better for makeup, etc. (or so the Boss tells me).

If you use two mirrors, then one lamp on each side and one between the mirrors all at about 68-72" above the floor.

Sconces won't work if this vanity is in an alcove or if it abuts one wall. I doubt there's more than 4" from the side of the vanity to the sink edge. A small sink base pushes your sink closer to the edge, which is why a larger sink base is a better choice. The mirror should be wider than the sink, eating up even more of the wall space. She'd have to use a full mirror and mount the sconces on the mirror. But if it's on a straight wall, sconces can sit slightly outside the edges of the vanity.

The shadows from overheading lighting are minimal. I would do sconces if it works with the design because they are a pretty look, but I think we place too much importance on side light source. If your make-up is that complicated, a wall-mounted lighted magnifying mirror is a better choice. Shoot, some women apply mascara while driving!