We like to visit Knott's for a change of pace and place. The food is good and the park has generally been clean and pleasant when we have gone. (We have only been 3 times, twice during Thanksgiving week and once during summer, so we don't have a whole ton of experience.) My advice for Knott's though would be to not finish there; either do it first or as a break in the middle of Disney touring. Also, don't expect it to be Disney, and you are less likely to be disappointed. I don't ride thrill rides but still enjoy the mild rides, shows, atmosphere, and food.
All that being said, I was going to advise you to just stick with Disney since it doesn't sound like you've been visiting multiple times per year for many years like I have, and adding one more Disney day wouldn't be too expensive or difficult. However, when I read your final comment on the CHOC walk I changed my mind. Do three days at Disney: Friday, Saturday, and Monday. Do Knott's on the Sunday. That way you get both experiences, you don't do Knott's at the end of your Disney trip, and you avoid any potential crowds and inconveniences of being there on a big event day such as CHOC.