Yes to Universal! Your boys are the perfect perfect age, especially because of MarioWorld. I’d check the height requirements again because my 40” daughter can go on almost everything … maybe just not the Mummy? I would absolutely go!! Get reservations to eat at the Toadstool Cafe when you’re there. You can only reserve day of using a QR code.

Yes to Disneyland. I’d spend a day at Disneyland and a day at California Adventure. You could do one a week so you don’t have to book a hotel in Anaheim if you don’t want to. Summer is not bad at Disneyland. Many SoCal residents’ annual passes are blocked out during the summer so it’s often less crowded than other times of the year.

Legoland I would also do - their water park is open at that time of year.

The hiking in Southern California is really nice so I’d look into that too. The mountains east of San Diego (only an hour away) like Palomar Mountain. Check out the historic town of Julian and try their apple pies.

If you’re interested you could head into the San Bernardino Mountains to the pretty towns of Lake Arrowhead and Big Bear. Mountain biking and other outdoor activities at Santa’s Village in Arrowhead.

Have a great time!

One day is possible at Disney but make sure you get there for opening time. We did 2 days at Disney (one in Disneyland and one in California Adventure) and did more 8am-11am than we did 09:30am-closing.

Skip Sea World, it is old and not that great. It doesn't have the crowds that Disney has and some roller coasters but definitely don't go there expecting any kind of Disney magic. The orca shows still feel exploitative and awful.