We had the same dilemma as you - we originally planned a two week holiday from Australia, principally to see
Disneyland, but then started thinking that as we had come all this way, we should see everything we could.
We therefore added on a few ays in San Diego just to see the Zoo and Sea World.
It added a lot of driving to our trip, but it was worth it - my daughters (5 and 9 at that time) loved it and we thought both were well worth the addition.
Sea World was a great a day - the shows and the animals and the rides were wonderful, and the Zoo was sensational, especially the pandas, the mountain gorillas and the apes.
I totally understand where Judy is coming from, and a few days rest at a quiet beach would be lovely, but sometimes when you take these special holidays from afar you recognise this may be the one time you get to see these places, and you just have to do as much as you can.