We had a shower in our last house that was almost exactly the same size and shape. I would: 1) ditch the bench. If you need a place to rest your foot for washing/shaving legs, then make it shallower and lower. 2) we had a fixed shower head (mine) on the short wall to the left as you enter (in your picture, the 28" wall), a handheld on sliding bar on the right (but that may not work for you because of the half wall - ours was full-height), and body sprays (worthless, we never used them) on the longest wall. This configuration worked great, and we often showered at the same time.

Expanding on what @roarah says, I would use a temp and volume control at each fixture if two people are going to use it at the same time due to preference in temps. In my one control shower with a valve that can switch from rain shower, water fall, and hand held spray, the temp does need controlling, as the hand shower is closer to the body and the water doesn't lose as much heat, as does the rain shower, as it travels through the air losing heat before it touches the skin. The rain shower head will be a nice head to use near the door, if you need to place one there. The regular shower heads would need more shielding with glass, from getting onto the floor. I have a 3' wide shower that is 5' long, with the glass on the long side. My doors both open in and out, at about 29" wide each. The 5' long wall is measured in the rough-in stage. It actually is 58" once tiled. My rain shower head is at one end and my hand held is next to it on the wall in a porter (small holder). It is not a problem reaching in to turn the fixture on. I primarily use my rain shower, and if I need a blast of water to rinse my hair, I use the waterfall feature. I hardly ever use the hand held except to rinse the shower floor. BTW I wipe the entire shower down with a large microfiber towel following each daily shower. I never have to clean my shower :) Its been in for 3.5 years and I only clean the pan every 3-4 months with a spray cleaner. My shower is spotless, no discolored caulking or grout. I have a stool that is portable in my shower. I would have had to put the built in at one end if I wanted to go that route. I like having the movable stool, I can move it under the rain head and just sit there relaxing, when I feel sore, sick, or just tired. I don't have a tub in the room, so this is the next best thing. I bought an inexpensive gray topped stool with aluminum adjustable legs, and I love it. It matches my gray shower pan. It is rather clinical with a modern look. It is light weight and easy to move. I thought about getting a teak stool, but couldn't settle on one that wasn't too expensive. I think my room is nice looking with my shower, fixtures, and shower seat. I have a lighted exhaust fan in the shower too. Have you looked at pics on Houzz showing what you want to do?

I would want to be able to control the shower without having to get into the shower and have water that is not the temperature I want falling on me :-). Therefore I would have controls by the opening which in your case is opposite from where the shower head and hand held will be. Don't forget to install grab bars since they need to be installed in the studs and so it's difficult to retrofit after the shower is tiled. They now have non-geriatric looking styles. I have essentially the same system as you do except I have a three way diverter since I installed two handhelds - one at each end of the shower :-). I do have a niche but I also installed a nice basket at the other end. It comes in a variety of finishes to match whatever fixtures you are using. Mine is oil rubbed bronze and it is a nice and functional accessory in the shower. Kohler Basket Also consider some kind of toe niche as it's handy for shaving legs or dealing with legs in general :-).

@cpartist the short wall? Does that work if two people want to shower at the same time? I dont know that I am a big fan of a rain shower. I was leaning toward a shower head on each short end and could add a rain shower in the middle if we wanted. That's what we had in our old condo and what we have now and yes, it works fine. DH uses the rain head and I use the one on the short wall. Rain head is centered on ceiling but there is a switch to turn it into a more regular shower head. I use the hand held. My shower is about 45" x 60". My old shower was 3' x 6'. Our shower now: Our old shower in our condo: I was leaning toward a shower head on each short end and could add a rain shower in the middle if we wanted. The problem with a shower head on the short end where you enter, is getting cold water when you turn it on. Your last version will work too.