For fathers day, I give a small family gift to my father and stepfather, my husband gives a small family gift to his.
When our daughter was young, I always included a special photo we took of our daughter and she would hand make the card for each of her grandfathers on fathers day.
Now the guys have mostly asked that we not give gifts, but go to a meal with them. I still take a small token. My father loves the movies, I give him a gift card to a local theater, my stepfather loves sweets and my mom keeps a tight rein on him, so I give him a gift card to Marie Calendar's for pies or candy from a local candy company. My husband gives his dad, some kind of fancy beer, steaks or cigars.
We really do not do anything for grandparents day except call.