If your grandparents are still alive, then you need to be thankful. Some people are wishing if they could see theirs just for a day, especially when people are talking about the good things they did when they were alive. As a granddaughter, your grandparents on both sides are the nicest people you should see.
The age difference does not matter. Inform your parents about your decision to spend your next holiday with them. If you are fortunate enough, some grandparents like having their ground daughters around. Most of them will tell you some things you don't know about your parents.
My grandparents are my best history teachers; they have seen a lot of things, and they like it when they are sharing those things with people. However, if you are too far from your grandparents, let them know you love them by giving them frequent calls, you can decide to be calling them twice in a week.