My personal opinion about Knott's is that it's not really that great. I went with my husband because he is in the military and it was free during a promotion they had, but if it wasn't free, I don't think I'd go. The place was dirty, the food was both gross and expensive, and the staff seemed like they couldn't care less whether or not we were safe on the rides. The only exception was the chicken dinner we bought outside of the park which was good.
I know this wasn't what you asked, but be careful on your day trip to Mexico. I live in San Diego, and there's been a travel advisory issued for Tijuana and nearby cities (across the border), which I would never visit ANYWAY, but definitely wouldn't now. There has been a lot of violence toward tourists, including deaths. Be safe!