I think I would do longer--but otherwise same--on the long side. Will there be room for a framed mirror on the short side with the switch plates there? If you center the mirror over the sink, there will be a big naked spot in the corner. Do you have a plan for that?

LOL, YES, I am on overload for sure. I can see the finish line or maybe I am the horse that sees the barn! We have been remodeling since 2011. Yes, we have a heater,, vent, nightlight combo in all bathrooms. I am a big believer in them. We are changing the mirrors, cabinets, lights, and the tub will be changed to a shower. The marble floor will stay. The previous owners put that same marble in the kitchen. You can probably imagine what it looked like after 20 years on a kitchen floor. It was awful to remove, so we will keep the marble floor in the bathroom. We will probably go with white and/or and gray tile because of the black and white marble. We have already installed a white Toto toilet. The electrician asked what I am using for lights. I had no answer because I didn't know he was coming today until he texted last night. I will try to get into a bathroom showroom Thursday. Thank you!

Depends on the mirrors -- are you covering each wall with mirrors, or will you have individual mirrors over each sink? If the former, then make the lighting proportional; if the latter, then same size over each mirror.

Yep, no natural light in bathroom, sadly. So I’ll have 4 canned ceiling lights (one is in shower) and 4 sconces with 2 mirrors. Lighted magnified mirror by my vanity for make up. Irritant from old bathroom was poor light and dark gray walls. Painter is scheduled to come before countertop is ready. We could go ahead and hang mirrors and sconces though. Appreciate your kind help. Thought paint was “the thing” to tie bedroom and bathroom.