It's really a no-brainer to install a surface-mounted medicine cabinet. Have the contractor install the vanity, faucets, etc. and then have someone hold the cabinet up to the wall to see if you have the clearance you need. If not, install the mirror.

I am looking at the same RH cartwright as well. I would definately do the small for a 36" vanity. I'm doing a small for my son's bath and his vanity is 48". Part of it depends on how you will do your lights- scones to the side of the cabinet or fixture above. We are starting framing next week. The joists and subfloor on the first floor are in. FYI, RH will have a bath sale shortly after christmas and I plan to purchase the cabinets then. I'm trying to decide which size to do in the master. We have 2 vanites and each will be about 54-57". The big one sounds enormous, or maybe it feels wrong for that style of cabinet. Any opinions? Here is a link that might be useful: RH cartwright medicine cabinet

I came here looking for similar information. I have 57-in width and a 36 wide medicine cabinet that cannot be flush installed. That leaves 21", or 10.5" on each side for these petite shaded sconces. Since the medicine cabinet definitely cannot be recessed, I'm trying to figure out if the sconces are going to look crowded next to the depth of the medicine cabinet. The medicine cabinet has its own lighting, so I'm not worried about that. The sconces will be room lighting if someone isn't doing detail work at the mirror. I guess I'm going to have to prop everything up and see if I can figure this out. I'm surprised there aren't guidelines or articles out there on this situation.

There is no photo. Many medicine cabinets have simple holes on the side, like a kitchen cabinet does. Maybe you can get simple shelf pins from a hardware store. You can get a glass shelf from your local glass shop.