Isnt it funny the different perceptions we have of different names. To me, being called 'nan' would have me picturing a little old lady with a perm and a rocking chair, granny makes me think of my granny who was very glamorous with lots of jewellery, wearing tea dresses and furs, beautifully made up and driving a sports car. Grandma is homely and wise.
My mum was going to be Nana but DS1, who was her first grandchild, could only say 'Anna' which is what she is to all 6 of her grandchildren. People who don't know find it very confusing as her name is Alice and she was called Babs by her family. 