We took our boys (4 and 5) to Blizzard Beach two weeks ago.
One thing of STRONG consideration would be the weather. It was simply not warm enough to really enjoy the water parks two weeks ago. The air temp was 81 on the day we went, but it was windy, and there is actually a lot of shade in the water parks so it did not feel hot at ALL. We were all freezing for 3 hours...
We won't be going back until our boys are MUCH older. While they did have fun, we found the kiddie area at BB to be a nightmare! It had about 4 different entry/exit points, and the part where they had to go up to ride the slides were hidden from view, and there are three slides, so we didn't know which one our boys were on. It was crazy! DH and I felt like we were going to lose the kids. After about 5 min, we left that area!
Plus, regardless of what people say, the water was NOT "warm". It felt very cold to us, especially in the lazy river. It was not nearly as warm as the resort pool (SAB).
I would maybe have one parent take your 14 year old, who will REALLY like it. Wait until the little ones are more independent and WANT to really go (as in, they ask YOU to go).
At this age (4-6), I strongly feel that if you are staying at a resort with a pool slide, they will be good with that. We were staying at Beach Club, and our kids enjoyed that pool more than Blizzard Beach...