We've been to the NC location several times. Just last month we went for 4 nights - originally going for 3 (first night was a $119 rate, got an email to add a 2nd/3rd night for 30% off lowest rate, so we did), but the day before we were supposed to leave our house, the power went out. We didn't want to sit around in the dark so we called and they had a room - not quite as cheap but they threw in a $50 resort credit and a 2pm checkout.
We (3 kids, ages 11, 10, and 6, plus my husband and myself) were not bored for a second. The water park was great, MagiQuest was a HUGE hit - my kids played it every day. Well worth the $$. We ate at their buffet once for breakfast (just "meh") and twice for dinner (surprisingly good) - and drove to Walgreens for snacks and fast food for other meals.
4 nights, 5 people, hotel and waterpark, Magiquest for 3, 3 buffet meals: Probably $1400? Sounds right. Other expenses were ice cream and snacks, and meals off-site. I think that's a pretty good deal. And the longest line for a slide was about 5 minutes.
Sign up on their website for their email alerts. That's how I got the best rate.