Hello, Teresa,
Three weeks in Walt Disney World! How quickly can I share with you how jealous I am? As for a section of
Disney's Coronado Springs Resort that isn't around too many children is a tough one to answer as Walt Disney World has so many families with children visiting all year long. However, there are a couple of ideas that may make a good match for you.
In Cabanas building 9B, all of the rooms are business class rooms, so they may lend themselves more to an adult crowd. Similarly, Casitas building 1 is located next to the Convention Center, so it may also have more adults there if your trip coincides with a convention.
I am going to also suggest taking a peek at
The Cabins at Disney's Fort Wilderness Resort. This is a bit more expensive, but it is still considered a moderate resort. The reason I thought it worthwhile to look at is because the resort is comprised of individual cabins, so you will likely have more space and quiet to yourself. You may also like the living and kitchen area that is part of each cabin since you are staying for 3 weeks.
I hope this helps to give you a few options for your Walt Disney World trip. If you have any further questions, please let us know. -Kara