This past September, my dh and I got a chance to go to Disney by ourselves. And it actually came about because of our kids. My dh's bday and our anniversary are a week apart (in Sept) and our 3 oldest (teen boys) wanted to do something for us. Knowing that I had a valid AP from our last family trip and that dh would be free on his bday, they actually went in together and bought our plane tickets.

They discussed it with dh's parents who offered to come and watch them all while we were gone and also picked up our hotel tab as their gift. It was a quick trip, 3 days/2 nights, but it was very special coming from our family. We did feel a bit guilty even though we have taken 6 family trips in the past 8 years.
But more than that, we just felt nostalgic at times. We would have those moments when we'd have a memory of one kid doing this, or another of all of us doing that, etc. Having all of our memories of Disney being as a family for all our trips and then it suddenly being just the two of us felt weird. Guess it just kind of opened our eyes to what our life will eventually be like when they all leave the nest.