I don't know if there is long-term parking at Union Station directly. I know that there is a lot there in the front, but don't know of the weekend rates. Could be ten dollars. But, I think with Olvera Street right there, you might not find weekend bargains. You may be just better off just driving directly to the Pantages. Where are you coming from? If you are going to Union Station, and don't want to deal with the Hollywood Freeway traffic, you can just take Sunset to Hollywood Blvd, and it probably will take you 15 to 20 minutes to get there. Plus, if you're seeing a show at the Pantages, you may run the risk of leaving the show and finding out that the Red Line stopped operating for the night (I really don't know what time they stop on the weekends).