I ski Mammoth about 3 weekends a month. I did the same in college, then went to Tahoe for 6 years, now I am back to being a Mammoth weekender. I absolutely love it, one of the best mountains in North America. It can get crowded on weekends, but as long as the whole mountain is open it spreads things out pretty well. I grew up in the east and the crowds were much worse there. The one thing I will say is to drive to the hill early, or use the shuttle bus because parking can be an issue. I usually park at Little Eagle if I can. The Little Eagle area has lots of beginner terrain, and from there you can easily get to Canyon which has all types of terrain for when you progress. Have fun, you will be skiing one of the great mountains on the continent. As far as LA mountains I actually like Baldy the best, it has by far the best terrain when it has snow. If I'm not going to ski Baldy and I want a day down south I usually go to Mt. High, it is closer and less crowded than Big Bear, which gets packed.