You really must have thing for Olvera St. I've never said it was the end all be all of Hispanic L.A. but the OP was just talking about visiting for a bit with their friend.

As far as Chinatown goes - um - have you seen the schlock stores there, or the signs in Viet Namese? Have you been to Alhambra? The very things you are saying about Olvera St could equally be applied to Chinatown. Bad costumes trotted out for holidays, schlocky tourist stores, and inferior restaurants.

While it is true that Chinatown was once the center of Chinese life in L.A. it is also true that Olvera St. was once a true part of Hispanic culture in L.A. Of course at the time that Olvera St was a truly representative of L.A. most of L.A. was Hispanic (moreso than even now). Both are now more designed to separate tourists from their money.

As a place to meet, have lunch, and maybe take a look at an historic house, there are much worse places in L.A. than Olvera St. I am sure you will disagree...