The first thing to settle about Islands of Adventure is whether your group clears the heights, because the answer changes the entire shape of the day. Fourteen attractions measure riders. Five of them - Hulk at 54 inches, Doctor Doom's at 52, VelociCoaster at 51, Hagrid's at 48 and Forbidden Journey at 48 - are the reason people buy tickets. A group where everyone is over 51 inches has one of the great theme park days in the country ahead of it. A group with a 42-inch child has about six rides and needs a different plan.
The second thing is Hagrid's Magical Creatures Motorbike Adventure. It is excluded from Universal Express Pass, has no single rider line, and posts the longest waits at Universal Orlando on most days. There is no product you can buy to fix that. You ride it at rope drop, you ride it in the last hour before close, or you spend between ninety minutes and two hours in a queue. Every other headliner in this park has an escape hatch; this one does not.
Third, do the Express Pass arithmetic before you book anything. Universal Express Pass is a paid front-of-line product sold per day, and it is included for every guest staying in a room at three of Universal's hotels for the length of the stay. On a busy day for a family of four, the nightly premium on one of those hotels can come in under the cost of buying Express separately - which makes it a hotel decision rather than a ticket decision, and one you cannot make retroactively.
Fourth, Islands of Adventure has six single rider lines - Hulk, Spider-Man, Doctor Doom's, Kong, VelociCoaster and Forbidden Journey. Disney parks have almost none. If you are two adults who do not mind being split up for four minutes, single rider is close to free Express Pass, and using it well is worth more than most paid upgrades.