While I don't LOVE Olvera street, I don't think it's as bad as all that. True, better food can be had elsewhere, but it is kinda cool to see where LA started and to go to the couple historic houses (sorry, I don't remember the name, but they are easy to find, its only a block long after all). Also, walk around the corner and tour the fire house. I don't think you can go down anymore, but next to the fire house was also the entrance to the Chinese catacombs.

Most of the lots in the are charge $5 or more to park, depending on weekday/weekend, but you can just park at Union Station and walk over if your friend is taking the train in. Don't know if I would make a day of it, but its not a bad way to kill an hour or two.