Hollywood movie premieres

So, I'm planning to go to LA this year, and I'd like to go see a movie premiere in Hollywood - one where the actors show up :p

Google failed me and I couldn't find dates of premieres, or how to get tickets for such an event.... do they even sell them to the public? Is it worth it/fun? Or just to say "I was in the same theater as a movie star, but I didn't actuall see him/her" ?

If someone who's been to such a premiere, or knows about it, could hepl me, that'd own~