And yes, Water World is a blast. When we went last year during our vacation, we got the Front of the Line pass as well, and one of the actors soaked us big time. We were near the front and he filled his bucket of water and literally walked over and just threw it on us, all before the show even started. They really mess with the guests, too, so it's a blast. We were so glad it was a hot day!
Mummy was the next attraction on this list, the one that just missed the cut. It's okay, but pales in comparison to Orlando, and isn't as worthy as the other ones on this list.
If you wanted to make this a longer day, I would do Mummy after Jurassic Park, then come up and break for lunch before doing WaterWorld and T2.