Those light switches definitely pose an issue. I assume you'll be putting a stool under the left side of her sink, for makeup and whatnot, which means you'll want the mirror low enough to see into while sitting down. That will mean you'll either need a lower placed mirror on the left side, with a higher mirror (b/c of the light switches) on the sink side, OR, you'll have to move the switches. Tough call.

Two individual mirrors for sure! Make the narrowness of them look intentional and the height will look intentional as well. To add to the intention, I would put individual sconce placed between the mirrors vs above <3

I like your husband's plan. If you need to buy a couple of inches to fit the mirror, have two of the four-pack of switches moved down by the outlet, in a triple box.

My husband's plan works with leaving the outlets. But was concerned the mirrors might be too small. Thanks all for your comments! We really appreciate them.

Nah, that's a good size. On both sides, hang the hand towel ring/bar on the wall with the mirrors, to fill the empty space (left on Her side, right on His), and then maybe a small picture on the left side of His vanity to balance the towel and lack of second mirror. It will look nice.