My dad and stepmom are already grandparents and use Papa and Mimi. Reminds me of Drew Carey, too, but that makes it fit her LOL
My mom passed away and we'll use Nana for her. I wish I knew what she wanted to be called.
MIL and FIL want to be grandma and grandpa (boring!) These are their first grandkids.
My aunt (mom's sister) will be their grandmother and since she already has grandkids, she is called Grandma and my uncle is Dude. Since MIL refuses to budge on using grandma for herself, I might encourage the kids to use Gigi (GG for Grandma Gail).
My grandparents were Tutu (Hawaiian) and Granddaddy as well as Oma (German) and Granddaddy. I was the first grandchild and my parents say I picked the word Oma without knowing it was actually a word for grandmother. Tutu loved Hawaii so she picked her name. I just didn't want any of our parents to use names we had for my grandparents. DH's grandparents were Grandpa First Name and Grandma First Name on both sides. meh