Haha, yeah everyone is telling me avoid L.A.
Salsa sounds interesting, will keep that in mind.
Hope the people in US are more friendly over there than on here, only 1 American has helped me so far
LA is a great place and has a lot to offer. People who hate it are usually intimidated by its size/sprawl and/or because they don't know where to go or what to do. Granted, it isn't the easiest place to get around, particularly for unfamiliar tourists, but if you have a proper tour guide, it can be great fun.
For tennis, there are free public courts all throughout southern CA - I've never paid money to play tennis.
LA has tons of great restaurants...as I'm sure you'll be around the gay area (West Hollywood) I recommend Bossa Nova (great Brazilian food) and Hollywood has my favorie Thai restaurant on the planet: Sanamluang. It's a hole in the wall, but has the best authentic Thai food and it's open until like 3 or 4am at least, so it's great after a night of clubbing (we ALWAYS went there after the clubs).
I haven't been clubbing up in LA for quite some time, so I don't know all the latest hot spots, but could ask around if you do stop in LA. West Hollywood has the bulk of gay clubs, so it would be pretty easy to find something there you like.
The Getty Museum across the freeway from UCLA is worth a visit.
I'm not sure exactly what type of "sites" you're interested in, but if you want a site for hookups, its adam4adam.
And if you're already in LA, San Diego would make a great day trip.