I waited until my youngest was tall enough for most of the rides. Since the tickets are expensive, I paired the USO trip with Sea World, and other non Disney parks. Cheaper overall than all at Disney.
If you can swing the $400 dollars, the parks can be fun for you little ones. The parent trade off is great at USO. The kid watcher and kid generally wait in a nice room and you can generally all walk through the line up to the loading of the ride.
In IOA, the Suess area is really colorful and fun rides. The Marvel area is very colorful and you can meet Spider-Man near the ride, and the Pteranadon Flyer will be fun for the kids too.
In US, the animal show is fun, there is Barney, a parade, lots of chances to meet characters, and your kids may be able to do some of the rides, like D. Me, Simpsons, etc.
If you sty onsite, the free unlimited express pass will spoil you.