been for Blizzard Beach or Typhoon Lagoon?? If neither, I would suggest doing Typhoon Lagoon before doing BB. BB is a good park, don't get me wrong, but Typhoon Lagoon is so much nicer and better than BB, just my .02.
We are a Water Park LOVING family! We have annual Water Park passes, that's how much we love them. I can say you will Easily spend an entire day @ either of them. The time flies so fast, you cannot believe it! We have to schedule an extra 3 days onto every WDW vacation just to go to Typhoon 2X and Blizzard once. Cannot miss them.
Keep in mind, if you're not using the NEW Extra Magic hours @ the water parks, the park opens @ 10:00 and closes @ 5:00pm (may be open later during peak seasons) so the day isn't really all that long. You will still have plenty of time to hit another park in the evening.
I would also strongly suggest, if your boys are water park addicts, to go to the water park early on during your trip. You will see what a complete blast they are and will probably want to go back! Have fun!!!