As someone that literally lives out of Marriott hotels 11 months of the year, I would love to see a curtain or blacked out window in the workout door. Some places have it, but a lot don't. It gets weird and awkward when people are looking into the window as your working out. Just recently in Minneapolis, literally 9 people came by and watched through the window.
On a positive note though, I do very much appreciate the partnerships some Marriotts have with local gyms. Keep up the great work