What is the a good size for a stand up shower with a built in seat

I want to have a nice size shower but I would like to have a seat as we are getting out and I need a seat. What size should the shower be and how wide should the seat be

Do you want your shower to be a manufactured enclosure or a custom tile shower? Do you have drainage already o be hooked up? Will the job be contracted out or will you be doing the work yourself?
Can you furnish more details? Regards, Tom