I stayed in two hostels in LA... the first was The Orbit, on Melrose Avenue, west Hollywood. The hostel was alright, they did mess up our booking so we had a dorm instead of a private room, but they knocked some money off for the trouble. They put on open mic nights and comedy nights there, and you can get food. Location-wise, it was ok, we could catch public transport from close-by.
Second time, we stayed at the USA Hostel Hollywood. The hostel itself was quite nice, and they organised lots of things, like trips to the theme parks (we went to Universal Studios, but actually did it separate to the hostel, as it worked out cheaper), walks around parts of the city, buses to the beach... and they had the most amazing band play there one night. But the area wasn't the greatest. We walked most places, but didn't feel particularly comfortable doing so at night.
I kind of wish we'd stayed at one of the beachy areas.