With a picture framer you tell them the exact size you want and then you pick the exact frame you want. They ask you if you want your mirror with a beveled edge or not. You don't need to settle on what they have already made. You don't need to buy a mirror and take it to them. They make what you want and for no more $$$ than Wayfair.

I think you'll make yourself crazy trying to squeeze sconces into the available space. I would find lights for above the mirror -- they could be sleek horizontal bars or something with a downward-facing light. People have been using those to get ready for decades just fine.

Depends on the shape, but I would think two 28 inch, or two 30 inch mirrors would look nice.

We will have a double vanity with two 36” cabinets with a 24” bank of drawers in the middle. Are these one connected piece or three separate items? If they're separate, that's a lot to take in visually, and -- if so -- you should keep the mirror and lights very simple /calm to balance out. We currently have one giant mirror Why not stick with the one giant mirror? With its larger view, you can see not only your face but also your outfit. It allows you a view of yourself without standing directly in front of it, and it makes the room look larger /brighter. In contrast, separate mirrors -- though trendy at the moment -- will add even more "pieces" to an already complex area. You can bring one large mirror all the way down to the cabinet, eliminating the "break" between counter top and mirror. The contractor wanted to put up mirrors with clips but I was hoping to find something a little prettier! Well, he's trying to do the easiest thing so he can finish with you and move on to the next paying customer. What matters more is that the mirror is "framed" -- either with an actual frame or more subtly with a bevel. This isn't a small detail, and it elevates your mirror from builder-basic. Someone else brought up lighting: I'd go with pendant lights at "eye level" -- this'll give you light at the spot you need it and will eliminate the shadows that come from overhead lighting. But if you stick with the big mirror, definitely put them on a dimmer, as they will be "doubled" in the mirror. No problem with having a separate light above the mirror -- just put them on separate controls. As we age, more light is more better. Bringing up one more detail: Consider mounting your faucets on the wall. This will make cleaning easier, as you won't have to clean around them as you wipe the counter top. If you can't do that, at least go with wide-spread faucets, which don't have to be "flossed" while you clean.