LA is full of board shops that sell lots of surf & skate stuff and dabble a little bit in snow. Surfside is the biggest and best of them that I've been to, but really not that much better than the little neighborhood spots because they're all pretty marginal overall. If I really need something specific I'll usually have to look around a lot to find it, or just wait for the next Mammoth trip and go by Wave Rave like Jimster. Take a look at the list of authorized dealers for the brands you're looking for and have a look around.
And I think a lot of us that have to live in LA all the time would love to move to Colorado for a while. A night out in Hollywood is a giant pain in the ass, and Lemmy smells terrible.
If you ever head down to the OC you might want to check out Surfside Sports. I've gone there for my board and my brothers. They have a pretty good selection, only shop I could find around me that sells never summer boards. The guys are super nice and can help you with anything.