The guest bath is a jack-and-jill one, with a small room with a sink coming off the hall, then a narrow room with a toilet and tub, and then a final ... not room, but niche in the guest bedroom with a sink in it, sort of like a hotel.

So there's no real space to put one except for in the tub itself, which won't do either as we discovered that our water pressure and hot water capacity is SO AWESOME that we can take showers at the same time without any change in either person's water. SCORE.