If there are swinger/lifestyle clubs in your area, they make good venues to be watched, and watch others having sex.
When we got our start in all this, we visited several lifestyle clubs, mostly during travel, paid their membership fee, and used the opportunity to get my wife comfortable with the idea of having sex while being watched - there is generally little to no pressure for her to have sex with others, although there were always offers. On premises clubs are all different, but almost all have rooms for this kind of play.