How old is your son? There are a number of things in the
Disneyland area that can be done as day trips.
Legoland, tends to be for the younger child
San Diego has the zoo & Sea World
Beaches all over.
Knott's Berry Farm & Six Flags for the thrill seekers.
Parks & sites all over to be seen.
Give yourself enough time at Disneyland so you can take it at leisurely pace so your son doesn't get overwhelmed.
We're going at the end of July with 10 people & our almost 3 yr old twins are autistic.....so we are planning on lots of breaks & doing 6 days at Disneyland...so not to feel rushed.
The 3 Disney resorts are all very nice but too spendy for our large family. The motels on Harbor across from the park are all pretty good. We've stayed at the Desert Inn & Suites & the Tropicana and both suited our needs fine. This trip we're staying at the HoJo, since we plan on spending more time at the motel. They have beautiful grounds & a swim pool & a water park play area for kids......I know we're all looking forward to this!!
Good luck with your plans!! All I can say is....let your interests guide you in researching what would be best for your family.