Thank you everyone for the thoughts! I’ll address the bathroom question first because I have DEFINITELY been back and forth on it. We are on septic, naturally, and had it designed to accomodate two additional bathrooms than what’s going in the house. At least one of these will be in the workshop/storage building nearly adjacent to the barn, so closer than the house for the emergency potty needs once the shop is built. ETA the shop will have a second floor to be finished out as an entertaining space or for long-stay guests. It’s certainly a fair point that a barn bathroom is more convenient for vet/farrier but I prefer to not add the additional permitting and cost that would likely be incurred. As for a boarder, the intent is to board an additional retiree to keep my old man company when young horse is off showing/lessoning/whatnot. So I don’t anticipate having heavy volume of foot traffic.
Overhang on the back - I didn’t think of adding a small overhang, will definitely add that to my list! The long side of the L will face east, so morning sun.
Wash stall - noted on moving the drain, I hadn’t even considered putting it towards the back but it’s super logical. I also like the idea of insetting rubber pavers or mat into the concrete.
Windows - I’d been debating to the window from office to wash stall and leaning more towards switching to two windows on that back wall. Or maybe add a window to the side wall, but the sliding door would almost always be in the way unless I also have windows on the sliding door… which isn’t a terrible idea either. Sorry for the stream of consciousness!
Dutch doors - I’m planning the runs for more of a lay-up sort of situation than constant use. The magnets are a super cool idea, will have to google that!
Keep the ideas coming!