The builder messed it up and did tell me today that they would change it. However, he did point out I might have a problem reaching the shower controls if I put the door where I want it. Therefore, they've agreed to switch it to a sliding door. It will solve all of our issues. I'll just have to get used to getting in the shower on the other end...but based on the couple responses it sounds pretty normal to enter the shower on the same side as the head. Thanks for the input!

I am in process of designing a shower with the same dimensions and questions. Same drain plan. Preliminary decision is to go with Kohler's hydrorail shower system which is exposed, includes the handheld diverter and supports a rain shower head on the 18" extension. That puts someone showering between 18-24" from the shower head wall. It leaves considerable space in back for a bench or a chair. The advantage to me is simplicity -- that system supports a single pressure balance valve and has an integral diverter. Alternately, to do a ceiling mounted rain head plus a hand held, a thermostatic valve is needed and the price escalates. For a master, I'd likely go with thermostatic. We have one in our master with a separate hand shower and it's excellent. But for this powder room bath expansion I think a single pressure balance (on/off) shower is sufficient. It's really a question of how the shower will be designed/used. I don't have experience with the hydrorail so I did do a post asking if anyone had used it.

Our shower is 6 x 4. We chose to install 2 valves. Valve 1 has a fixed showerhead and a rain shower on a 3-way diverter. Valve 2 has a handshower positioned near the teak corner bench. For a true dual shower you might want to install 2 fixed showerheads on opposite ends, and one central rain shower. For ease of cleaning, you might want to change one of the fixed showerheads to an adjustable handshower on a slide bar. It will still work the same as a fixed showerhead, but you could use it to rinse the shower down after cleaning. If you post a drawing of the shape of your shower, where the door will be, etc, etc. people can weigh in more.

@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.