Typically a wainscoting is about 42" high. How high are your light switches from the floor?

depending on your ceiling height, the ideal is one-third to 2/3rds either way. I've used travertine floors and 6ft of travertine on the wall with a stone cap, topped by three feet, minus the crown, of paint above it with excellent effect. otherwise 33-34" in a regular room [8'] with a trim of choice no higher than 36" . in a bathroom you have other factors like counter and window-sill heights, backsplash issues, shower tile, toilet height, medicine cabinets, mirrors etc. you want to avoid too many different horizontal lines in the space, so consider all factors before deciding.

just avoid the half and half, please.

That Is wonderful! My husband wanted to do 42" but I wanted to be sure that it would look good. Our switches are higher than that. Thank you for your help.