My husband’s family recently welcomed the first-born of the fourth generation. (His cousin’s child.) And since the little one has started babbling we all figure it will start talking before we know it, and folks are trying to decide who should be called what. One day when other cousins start having children we’d like it to be where someone can call out “Grandma!” and only one, rather than four, heads turn. So I’m making a list of possible options…
What do/did you call your grandparents?
On my dad’s side, they were Gram and Granddad. On my mom’s side, it is/was Grandma and Granddaddy.
Grandmaman and Grandpapa for the French-Canadian side of the family, and Momo for my other grandmother (her male counterpart was never in the picture).
Not sure where “Momo” came from - I think one of my older cousins was the first to use it and it stuck, so we all learned that as her name.
Maternal: Grandmother & Grandfather (he died before I was born, but my brother knew him)…oddly, they were the more laid back grandparents
Paternal: Grandma and Grandpap
My kids call my parents Gamma (invented by my nephew) and Pap Pap. My husband’s parents are Grandma and Grandpa (deceased).
It was a long time ago, but I only remember Grampa & Gramma (I guess the D was in there but very slurred) for both sides.
Both my grandfathers died when I was very young, so I don’t remember them. My father’s mother was Grammy and my mother’s was Grammaw.
Everyone on my mom’s side of the family goes by first name, including grandparents. On my dad’s side (German, living in Germany), they were Omi and Opi.
My mom and dad are now Omi and Opi to my sister’s kids, while my brother-in-law’s parents go by Nana and Papa.
When we were kids we called them by particular nicknames they’d gained (e.g. my maternal grandmother could make a “cuckoo” noise by blowing into her hands, so I dubbed her Cuckoo, and the name stuck).
When we grew up, by their first names. None of them wanted gran- anything.
For my sisters and I, our grandparents were Grandma and Grandpa Lastname.
Since two of my grandmas are still alive, they’re still Grandma Lastname to everyone, even the great-grandkids. My mom and the other grandmas go by Grandma Firstname. My dad’s just plain ol’ Grandpa or Grandpa Firstname.
Grandmother on my moms side is Grandma Norma. Her dad died about 8 years before I was born, so I obviously never knew him to call him anything. Grandmother on my Dad’s side is Granny. His dad died shortly after he married my mom (I was 3) so I don’t recall what I called him.
Nana and Granny. My grandfathers both died before I was born.
Paternal - Grandma & Grandma
Maternal - Meemaw & Peepaw
What about Grandmother/Grandma <Lastname> and Grandfather/Grandpa <Lastname> for each side? 
Abuelito y Abuelita
I guess this works when refering to them around others, but that would get annoying to call them everytime, and the primary reason we’re looking for ideas is because my husband’s parents and his grandparents are all living and reside next door to each other. So we need names that can be used when everyone is together.
A good friend of mine called her grandmother “Bunchy.” I don’t know why, and neither did she.
On my dad’s side I had ‘Grandmama’ and ‘Grandpapa’.
I never knew my mom’s dad. I still call my mom’s mom ‘Bubu’, which is Yiddish. A lot of my cousins’ children call her ‘Grandma Bubu’ to differentiate her from their other grandparents.
Grams, Grammy
Pops, Poppa
Neither grandfather lived past my 7th birthday. One I called Granddad and the other I called PopPop.
Both grandmothers were Grammy when I was young. As I aged they were Gram.
Maternal – Grandma Lastname and Granddad. Also a great-grandmother who was Grandmother, and the other was Grandma Lastname to me.
Paternal – Grandma Lastname and Grandpa Lastname.
I’ve mostly dropped the last names, mostly because my paternal grandmother and maternal grandfather have both died, and I’m sadly (and cowardly) out of touch with my dad’s family. (One of these days I will work up the nerve. It wasn’t deliberate. But that’s a whole thread in itself, really.)
Dad’s Side, Grandma and Grandpa
Mum’s Side, Grandad and Gran. We called her Granny if we wanted to wind her up. She hated it. Same trick works on my mum now she’s got grandkids.