Harry Potter is our reason for going and our only must-see. My question wasn't about what day to go. I'm wondering what else we should see.
The day you go will change what you are able to see. A touring plan for Thursday will be different than a touring plan for Saturday.
Also, Forbidden Journey is a relatively fast, dark, scary and at times noisy ride. The two other rides in the Wizarding World are roller coasters. Since your son, who loves Harry Potter, is not a fan of these types of rides, perhaps you should re-evaluate which rides your family would be interested in. The website,
www.universalorlando.com gives good descriptions and some videos of the rides. Youtube has onride videos of pretty much everything.
On a normal day, I would head straight for Ollivanders. Then do Forbidden Journey and FLight of the Hippogriff. Then head to Jurassic Park River Adventure and then Spiderman, Dr. Doom and Hulk. I'd then head to Seuss Landing and do all the rides there. I'd finish off with rides on Dragon Challenge. If your family likes water rides, Popeyes is fantastic.
Then I'd head over the Studios and do Transformers, Despicable Me, Shrek, Mummy, ET and Men in Black. There is a kiddie area there as well that the little ones can play at.
If you go on a busy Saturday, you may not make it over to the Studios. If you go on the Thursday, you should be able to get the highlights of both parks done.
If you want to avoid rides, there are some cute shows and other attractions. Sinbad might be fun for your crew as well as the Jurassic Park Playground and Discovery Centre. Storm Force Acceletron might also be a thing the entire family can do.
At Universal, The Animal Actors show is also cute for kids. There is a Spongebob meet and greet as well as one with Dora and Diego.
Rides that are loud and scary or dark or fast.... Forbidden Journey, Dragon Challenge, Jurassic Park River Adventure Spiderman, Poseidan's Fury, Hulk, Dr. Doom, Rip Ride Rockit, Mummy, Terminator.
Touring Plans aren't really used at IOA/Universal but you need to be familiar with which rides you want to ride and which rides are suitable for your family.