Originally Posted by JoeLena
I thought the lights over the shower/tub had to have GFCI protection. So using 2 new breakers, one for the lights and another for the receptacles might suit me better. I have another unfinished bath in the basement. In the future I could use these 2 new breakers for it as well.
I don't think, unless the manufaturer says so, the shower lights need to be GFCI. In-shower fans do.
I'd also recommend the 20A dedicated outlet circuits, one per bathroom, and a shared 15a lighting circuit. If you do a shared lighting circuit, just put the junction box where you split to the two bathrooms in a spot where you could easily tap into it for your basement bath.
You could also tap into one of the dedicated outlet circuits for your basement bath, might not be bad if your basement bath isn't used often enough to warrant a dedicated outlet circuit. This would be ok, since the circuits would be "multiple bathrooms, outlets only".