Hi John!
First of all you are not an old grandparent! You are young at heart and enjoying a Walt Disney World vacation with your family is going to be an amazing and wonderful time. I too am a grandparent and I feel like a kid again when I walk through the gates of the parks. My great love for Disney is because it is for all ages and all ages can enjoy it together.
When you are checking out
Resorts for your stay you will see three categories: Value, Moderate, and Deluxe. The Value resorts are the only ones that have the double beds and the rooms are the smallest and more basic. But don't get me wrong, they are very comfortable and very adequate especially if you are not spending much time in the rooms. I often suggest guests check out the moderate resorts as they offer just a little bit more in the amenities and each of the rooms will have queen beds. The Deluxe resorts offer queen beds as well and the biggest draw to these resorts is that they are all located close to one of the theme parks.
The standard and preferred rooms are exactly the same room with the same amenities but it is the location at the resort that differentiates them. Preferred rooms will over look nicer views or be close to areas such as pools or main lobby or dining. Standard rooms might overlook parking lots and be further from the "action" areas.
If you are traveling with a large group of family members you might look into the Villa options that have two and three bedrooms. Also check out the Treehouse Villas where you have a large area with many different bedroom choices. A moderate resort that offers more room and amenities are the
Fort Wilderness Cabins. These sleep 6 and have fully equipped kitchens. They are also my family's favorite! Fort Wilderness is an incredible experience!