I just got that setup myself. Horizontally, it's in the middle. The person taking a shower can adjust the shower head up and down depending on their height.

We have a 24" slider bar (Grohe) and the top end is 82" above the shower floor. My husband is 6' and he doesn't slide it all the way up.

-Babka

Depends how you plan to use the hand shower. We have two. The one in our basement guest bath is on a long (40") bar, and we positioned it so that it would be a good head height for my 5 foot tall daughter, and we placed the fixed shower head high enough for my 6 foot son.

We used this bath for 4 years while waiting to reno our Master BR (sigh). I liked to have the hand shower set at a height to hit my lower back, also low enough to grab easily while cleaning shower, shaving legs, etc.

In our Master BR (finally done), I have the bar set much lower, as it will ONLY be used for lower back, for shaving legs, etc. I absolutely love standing under rain shower setting on fixed and having hard massage setting on hand held aimed at my lower back.

Our house was built by very tall people, so we have gotten used to having everything a bit higher than normal! I am remodeling and going with a 48" slide bar in our shower. This will allow me to have it very high when standing or low enough to be used if you want to sit at the bench. We also have a separate fixed showerhead.

DH had foot surgery last year and that influenced some of the features we are adding in our remodel. The slide bar is thicker than normal and also rated as a grab bar. I also added a second grab bar.