Hi Hillary,
Thank you so much for visiting the Disney Parks Moms Panel with your question! I know just what you mean. My husband and I always want a separate space to relax once our daughter has gone to sleep. The Disney Vacation Club villas are perfect for this. Whether it is heading to your balcony or patio in a deluxe studio, or taking advantage of the separate living area in a one-, two-, or three-bedroom villa, the Disney Vacation Club villas offer spaces for families to relax and unwind.
Of the two resorts that you are considering, I would choose
Disney's Old Key West Resort over
Disney's Saratoga Spring Resort & Spa. To a certain degree, this is a matter of personal taste. The two resorts are fairly similar in many ways, including a large, sprawling layout and location close to Downtown Disney. My preference for Disney's Old Key West Resort is twofold. First, I love the laid-back feel of this resort. It is themed to the Florida Keys, and I find this to be relaxing. If you prefer a theme of horse racing in upstate New York in the 1800's, you might enjoy Disney's Saratoga Springs Resort & Spa more. The second reason is space. The villas at Disney's Old Key West are very large. Comparing the same villa size, say a deluxe studio, from one resort to the other, there will always be more space at Disney's Old Key West Resort.
I hope that these thoughts are helpful for you, Hillary. Have a great time planning your vacation, and please do not hesitate to ask if you have any further questions!