We recently vacationed at the Great Wolf Lodge in Williamsburg, VA. The Great Wolf Lodge has an indoor waterpark that is included in the price of your stay. It's not all inclusive, as dining is not included, but there are several eateries on site so you could comfortably never have to leave. My girls (age almost 4 and 9) enjoyed the waterpark so much (as well as my husband!). They spent hours exploring the many slides and pools the park has to offer.
Our accomodations were wonderful. The entire hotel has a "log cabin" theme which they carry out well into the rooms. We choose the Family Suite which included two queen beds as well as a semi-separate living area with a couch. It was perfect for us, but had we wanted more, they offer nicer suites such as a Kid's Club one with bunk beds and a cabin feel. My kids adored this hotel. It reminded me of Disney, their attention to children and details.
The food offerings were pricey, so we opted to leave the hotel for more familiar dining options (plus I wanted to shop!) Overall, for the price (we paid about $200 for one night) it was a very affordable trip that my kids won't soon forget. There are several Great Wolf Lodge locations around the country.