Universal Studios...ugh. I tend to dislike the obviously-made-for-tourist locations, but your mileage may vary.
If I only had three days to kill in the Los Angeles area, I might propose these destinations:
1) The Getty Center. Admission is free, and it's a world-class museum. The buildings themselves are art, and you get a great view of Los Angeles from the hill.
2) Santa Monica Pier/Third Street Promenade. It's a great place to walk around, peoplewatch, do some shopping, and get lunch during the day.
3) Hermosa Beach Pier. If you're looking to check out some bona fide L.A. hotties at the beach, Hermosa Beach is the place to go. At night, the pier is the place to be for nightlife -- there are multiple clubs and restaurants to check out if you're 21+.
4) Six Flags Magic Mountain. I dunno what the rollercoaster situation is in Australia, but Six Flags kicks ASS. There are some unique and impressive coasters there that you won't forget. It's a bit of a drive out of Los Angeles (maybe 45 minutes or so?) up to Valencia, but it's a must-go if you're into thrill rides.
5) Dodger Stadium or Angel Stadium. If you're into baseball -- or just curious about it -- then try to catch a game while you're here. Although Dodger Stadium is allegedly an icon, Angel Stadium is more modern and comfortable. On the other hand, you can get a nice view of downtown at night after a Dodgers game, so your mileage may vary.
6) San Diego. Yeah, it's a 2.5 hour drive from Los Angeles to San Diego. But, if you can somehow justify spending a very long day for a there-and-back trip, you could check out the San Diego Zoo (OMG amazing), catch dinner in the Gaslamp District, and then head home. SD >>>> LA
