They stayed with my Dad all the time before he died. The kids absolutely adored him, and he was a pretty big fan of them too.

They spend most of the summer with their Dad's parents because he doesn't really want them around, he just knows that he still can control us somewhat by making them come to Florida every year. So he ditches them at his parents ALOT.
Occasionally they will spend the night with DH's parents. Especially if they go camping and DH or I had to work. The kids love to camp and they knew that so they would always take them too.