I've lived in Socal for 3 years now skiing mostly at Mountain High. It's a small resort but the park is incredible every year and you can ski till 10pm most days of the week. Most of the mountains in SoCal are pretty small (Big Bear, Snow Summit, Mountain High, Snow Valley, Baldy) and the snow can be iffy. I live about 30 minutes from LA and an hour from Mountain High. I can't comment on the music scene, but it's LA so I imagine it's pretty good??
Plus once the snow melts, you've got any beach at your disposal. But, as Twoods said, the skiing is not that great outside of Tahoe and Mammoth.