am curious about the towel ring location. I have a similar layout, and the "obvious" spot seems to be as AJCN suggested, but ti's so near the outlet that I wonder about that. I guess it's not a concern.? In my instance there is a tad more space on either wall. Color wise I have similar flooring and have been strongly considering SW Sea Salt which is similar to watery. I think those colors are nice, but I think the lighter ones considering the dark vanity would work better. In our guest bath which has white flooring and white tiles/tub, I think I really like the Really Teal and the Lagoon. (but we have no windows there just the vanity lighting).

IMO the layout is part of the problem and we need a to scale floor plan to really help.How much money do you have to spend. Start with the lighting get some good fixtures with LEDs in 4000K also the pot lights cajnged to the same LEDs that will at least modernize the lighting. I dislikrejacuzzi type tubs and it looks like you have a small walkin closet . I would wait until you can redo the layout, do you need a tub , would you like a bigger shower I think a complete gut and redo would be a huge improvement and also good ROI when you go to sell.

You have opened up quite a can of worms with this project! Since the pipes appear to be galvanized iron, I would suggest repiping. That stuff is probably at the end of it's lifespan. Is some of the subfloor nailed in between the joists? I've only seen that once or twice before.

Yes you need a professional plumber to fix the mess-that little accordion-looking pipe is definitely a handyman special. You mentioned the shower was extended-I’m almost afraid to ask...did the same handyman extend the shower?