Lots of cool spots downtown:
-Check out LA Live (yeah it's touristy but who cares) and have a drink at The Ritz Carlton @ LA Live.
-Bars: Seven Grand, Edison
-Food: Wurstkuche, The Lazy Ox Canteen
Definitely hit up the Getty Center and/or Getty Villa (in Malibu). Two completely different experiences, both worth doing.
Disneyland during Xmas time is pretty awesome. Plus they have a new show at California Adventure that is pretty great.
Second the poster who mentioned Mastro's. Fantastic steakhouse.
Old Town Pasadena (start and Colorado Blvd & Fair Oaks) during X-mas time is pretty nice also.