There has been another discussion about this (I began it for similar reasons) and someone said that it is nice to think about your own (great) grandparents & use the name of one who meant a lot to you.
What is interesting is what we like / hate (see post above) I cannot imagine being a "grand" anything - if my suggestion of simply using my given name is not accepted (I think it won't be!) then I shall have to be nanny or nana.
In my part of the world all the men are grampy/gramps - you will so often hear a tale beginning "the old gramp allus said...."