Well, though it wasnt in dating, occaisionally I would take my kids on the Metrolink and check out the little shops on Olivera St. Other areas are mentioned in here though, such as the trams, chairlifts and the beaches, but keep in mind you might want to check ahead of time, some of those places are seasonal.
And steer clear of Lake Perris. Its no longer the pretty, fun place it used to be when my cousins and I would go there.

I used to take the kids to Dodger staduim once a year.
How close or how far from L A would you go, for that date?