We love Knotts at Christmas and go right around that weekend every year (First Responders get in free during that time frame). Ghost Town is decorated for Christmas and there are special snacks, old time carolers and Santa's Barn (free Santa visits if you use your own camera). The historical rides (log ride, mine train, stagecoach, etc) are my favorite and my kids love the thrill rides). It will be busy but not
Disneyland busy (ie packed). It is on a different level from Disneyland but my kids love it equally, and it was my favorite when I was a kid. If you enjoy the coasters I'd recommend it.