Hi Heather!
Congratulations on your upcoming vacation! I think you'll find that all of the Disney resorts are not only appropriate, but absolutely magical for kids (and grown-ups) of all ages. All of the properties have amazing pools, well-themed immaculate rooms, wonderful dining options and access to Disney's convenient transportation system. In addition, you'll be able to use Magical Express, a FREE luggage and transportation service from Orlando Airport, and take advantage of extra magic hours.
If you are looking to economize on lodging, I would look into the Value Resorts. I recently toured the All-Star Music Resort, and thought it was fabulous! If your kids are sports-fans, All Star Sports is a great choice. The moderate resorts offer rooms that are a bit larger (honestly, not significantly larger) and slightly more elaborate pools. In addition, they each have at least one table-service restaurant in addition to a food-court style venue. This year, Disney has offered some amazing packages and specials to help family's get more for their money. Currently, it there is a "buy four, get three free" package including park tickets that is one of the best deals I've seen to date! The package is available for many nights through August 15th. Hopefully, this covers your time frame. Historically, Disney has offered outstanding packages for late August and the early Fall as well (including free dining). While nothing has been announced yet, keep checking the website for specials in this time frame.
The independent website
www.allears.net has excellent, detailed pictures of all of the Disney Resorts and is a great place to get a "sneak peak" at the properties you are considering.
Have a wonderful trip!
Tanya