Knotts is a little run down, if you like really wild throwup type rides then you will enjoy it, otherwise give it a miss...
Soak City water park was excellent value, go online and search for the vouchers. we paid $27 per adult and $15 per child and if the weather is hot makes for a totally different day to DL. You can easily get there by bus if you don't have a car.
Also in Buena Park is Ripleys believe it or not and the Movieland waxworks you can get combo packages for both of these.
Block at Orange was the best shopping centre and easy to catch on the local bus.
Hope this helps