We have a window to the outside in our shower/tub. It had some rotten wood that I'm repairing and I'll need to repaint the whole thing. Due to constant moisture in there and probable expansion/contraction, should I use exterior paint when I repaint the window or just stick with semi/gloss interior?

Be sure to prime the wood first and then use exterior enamel for decks and siding. Curious how you repaired the rot

I don't repair rotted wood anymore, I use PVC board and trim. You can get almost all profiles in PVC today, particularly interior trim. Never have to worry about rot. You can even overlay the old boards and then put larger trim on.

I used a PVC 1x4 for the bottom sill and cut the proper angle into the bottom of the sill with my table saw. Although the sill was pretty rotten, everything underneath was in pretty decent shape. I chipped out what little bit of bad wood was there and poured epoxy all down in there to stabilize everything before gluing and nailing the sill back on top of it. The only place we have here for molding is Home Depot and as this house was built in 1946, of course there was nothing that would match. So I cut out all the rotten part as best I could up into good wood. Then I filled everything with Durham's rock hard putty and sanded the profile of the stop molding and the trim molding into the putty after it had set up hard a couple days. It was only 2 to 3" worth and I think once it's caulked, primed and painted it'll hold because there was a good hollow in there where the putty could mash up in and get a good hold. We'll also probably be replacing all our windows soon, so if it holds a couple years, it should be good.

I did think about tearing out all the old trim and replacing everything, but as it's laid into ceramic tile that I'm guessing was installed when the house was built, I could see a small project turning into a VERY LARGE project, if you know what I mean! :) I don't want to open that can of worms until we're ready to remodel the entire bathroom, tear out all the old ceramic tile, fixtures and everything.