Both of my grandfathers were dead by the time I was born. Paternal GM was "Grandmother Lillian", and maternal GM was "Nana" (Nah-nah). My mother also wanted to be called "Nana" by our kids, and their other GM was called Nana too, but pronounced Naan-a.
I thought I wanted future GKids to call me "BonBon" (my name is Bonnie), but maybe Grandma is simpler. Hubby will probably be a "paw paw".