This is my family's first trip, although my husband and I both went in our other life, before kids.
We got the Park Hoppers. I love the idea of being able to go to the Magic Kingdom in the morning, then choose one of Epcot's many wonderful restaurants for dinner. Likewise, we can spend the morning at the Animal Kingdom then see the fireworks at the Magic Kingdom. For us, I think it's money well spent.
I opted NOT to get the water park options. For starters, we're staying at the Polynesian-- that volcano pool looks great!! Secondly, there's a water park 45 minutes from here. I would rather spend our Disney time (and money) at someplace more uniquely Disney.