Diana...Here is link to the 72"VANITY https://www.homedepot.com/p/SUDIO-Jasper-72-in-W-x-22-in-D-Bath-Vanity-in-White-with-Engineered-Stone-Vanity-Top-in-Carrara-White-with-White-Basin-Jasper-72W/314491746 Per your suggestion here is link to a black matte 24 x 36" oval mirror that I just found. https://www.homedepot.com/p/Umbra-Hub-24-in-H-x-36-in-W-Oval-Black-Modern-Mirror-1006044-040/30520501 I am thinking of keeping the vanity's included nickel hardware and adding matte black faucets. Do you think the mirrors 24" x 36" ( hung vertically above each sink) is a good proportion for the 72" vanity?

If you do 4 sconces, 2 for each mirror, it will make each mirror seem its own entity, IMHO. If you do a double sconce in the middle, it seems like.....an after thought? And the sconces will not be equidistant from each other and the mirror. My OCD kicking in, I suppose. If the space between is larger than the mirrors, I think you should go with 2 separate sconces. If the space is smaller than the mirrors, I think you could go with a double light. Just make sure the spaces are fairly equidistant.

Great design concept! Two mirrors with 3 sconces could work for your space if you are willing to scale down the mirrors a bit. Because there are multiple variables to factor in the centering of the mirrors, consider condensing your variables to ensure accuracy and execute a thoughtful design. If you are open to it, two smaller framed mirrors would be a great alternative to custom millwork but still offer a rich, customized look: Going this route, you will have a little more room to space out your sconces appropriately and center your mirrors without compromising form or function. Best of luck with your project!

A double light over each sink should be sufficient with a window and assuming the shower is directly across from the vanity and that is the extent of the room. Other options are three single sconces mounted on the mirror and an over head light to give more light to the shower. I have a four-light over a 60" vanity in a 5x11 windowless room. The vanity area is well-lit. The shower at the end of the room is a little more shadowed but not enough to make showering and cleaning an issue.