The usual places, beach, movies, car, etc.
When I was in high school, my gf and I would go to into the homes that were being constructed in her neighborhood. It was a very nice neighborhood with very large expensive homes. They never would lock the doors to these places so we would go for a private tour of someone's new home and then do the deed where ever we say fit.
We say all the different stages of construction and moved on to the next house once they got around to installing the lock on the front door.