Most college men's lockerrooms/showers a great place to spy on student bodies.
There are also a few day spas in LA with lots of nudity:
CITY SPA - Pico Blvd at Burnside (co-ed at certain times with swimwear required at those times)
www.lacityspa.com
CENTURY SPA - Olympic Blvd near Crenshaw (seperate men's and women's facilities)
www.centurydayspa.com
GRAND SPA - Virgil and 6th Street (seperate mem's and women's)
www.grandspala.com
An all male spa on Wilshire, opened 24/7.
Heard of a sauna spa in the valley but I have never been:
FINLAND BATHS on Moorepark in Sherman Oaks.
www.finlandbathsmassage.com