I've always appreciated them NOT installing towel racks or TP holders in advance as I prefer to make those decisions myself. An item like a TP holder is one I don't want to ever have to move so it's screwed into the wall solidly and permanently. You can take a look around and determine where wires are likely to be running. I have three towel racks and ONE (the loop rack by the bathroom sink) was installed at the factory and the other two were furnished but uninstalled. I permanently mounted one on each bathroom door.
INside the shower I mounted some "command strip" hooks for hanging wash cloths and wet items (four of them) and we use the top of the shower surround as another place to hand wet items so they can drip into the tub/shower.
Each bathroom door also has "over the door" type of hooks (2 on each door) for hanging clothes, dish cloths etc.
Good luck / Skip