Michelle, my husband and I have gone on several trips to Walt Disney World without children and have loved every minute. The dates you will be there will be on a more crowded side because of Labor Day weekend but it should still be quite enjoyable if you plan ahead and make dining reservations etc.
I have several suggestions for resorts and ultimately the final choice will be about how much you choose to budget for accommodations. Pop Century is a great value choice being the newest resort in this category and also it tends to have less of the big groups staying there. But if at all possible I think you would really enjoy Port Orleans French Quarter or Riverside. The atmosphere is romantic and relaxing with a few more amenities with this resort. You can enjoy the boat ride to Downtown
Disney Marketplace or catch the busses to the parks.
In each park you will find abundant rides and attractions to enjoy. There are numerous great
dining choices as well as night life. The
Boardwalk area is a fun place to visit with several clubs available when the parks are closed.
Cirque du Soleil is an amazing show if you are able to catch a performance of that while you are there. The magic at Disney isn't just for children.....adults will love every minute of their stay as well!