FYI San Diego is a WAYS from
Disneyland like 1 and half hours with NO traffic so if you plan to do San Diego I would go at the beginning or end cuz it is a long drive to do in the middle of a trip. But if I HAD to choose I would do the zoo. There is much more to see there. They have a cool double decker bus tour and a sky tram and it has lots to see and do. The Wild Animal Park is neat too but if I had to choose 1 I would go with the zoo.
We are doing that exact trip this summer but driving straight to SD and going to the zoo the WAP and Seaworld the first 3 days and then driving back up through Anaheim (we live in northern CA) and doing a day at DL, DCA and Knotts.
If you have any other questions feel free to ask.
I do know you can get adults for kids price tickets on getaway today and I saw too a san diego card that gets you a bunch of attractions but it seemed a bit complicated to me cuz you have to exchange a voucher at the chamber of commerce or something. But anyway hope that helps.