I don't know who your traveling with (age-wise) but I have stopped going to Knott's all together because of the "bad crowd" that they attract. We live nearby and it really has gone down hill. The last time we were there my 5 year old found a used condom under our dining table (while we were eating), our 8 year old was pushed in the bouncehouse and got a good sized burn on her leg, I can't even count how many times rude teens (and adults) ran into us while walking, cut in front of us and our camera was stolen from our stroller while my husband was pushing it. (kid dropped change nearby and bent down to pick up-grabbed our camera at the same time!)
If you have younger or curious kids, I would suggest the Aquarium of the Pacific in Long Beach -it could be a full day attraction. The exhibits are wonderful, it is a very casual atmosphere and relaxing while being educational and interesting.They have a website if you'd like more information.
For younger kids (9 and under) I would also recommend Legoland in Carlsbad over Knotts. Much more relaxing, kid friendly, non-existant lines and reasonably priced food.
If you are looking for thrills than Magic Mountain is the place and it has actually cleaned up (as far as rowdies) recently.
Something else to consider, Now through June are prime season for school parties at Knott's which means even more crowds of unsupervised kids. They offer discounted tickets to schools all over SoCal and kids by the busload come from hours away for end of the year parties.
Good Luck, Andrea