My brother used this forum a few years ago and did a great job remodeling his Master Bath. That's saying alot... he's an Attorney...
My turn... (I'm an Engineer so am planning on totally screwing it up!!!)
I've got two teenage sons who are (or will be) of average height 5'10"), and a daughter (9) who is a Little Person. She will most likely not be much taller than 4' at her adult height. We are remodeling a bath that they will all share. I've done some measuring on my daughter and here is some Ergonomic information that is relevant to this question.
She is 3' 8" right now.
Her "reach" is about 8".
I figured that a comfortable counter height for her right now (Vanity elevation) is about 25"
I am building a custom vanity for her so she won't have to step on a stool or other platform. Little People struggle with having to work in Kitchens and use bathrooms built for average sized people. Imagine carrying boiling pots of water from the stove to the sink to dump some pasta. How many times will a mother do that in her life and what are the chances she will slip while stepping up and down? Similar hazards in bathrooms... Okay, end of soapbox..
Anyhow, the shower is the challenge. With space enough to put in a prefab corner shower (want to avoid hazard of stepping over edge of bath tub), I'd like to set up the shower with two heads and one set of controls. I envision one head on each of the two walls and the controls being at a height that is a compromise for all three kids who will all soon be at their respective adult heights. I don't care for the shower head on a "wand" as our water is very hard, and I don't want the complexity nor fragility, nor cleaning burden of all that stainless steel "hose" and hardware. All those units break anyhow after enough use.
Two simple heads at two heights seems to be the best choice.
So how do I plumb it?
1 diverter and 1 valve?