Since this thread's been resurrected, I'd like to add to it & get the forum's opinions as well, rather than start a new thread. My daughter is 2 years old, and getting better at speaking all the time. I'm fortunate in that both of my maternal and paternal grandparents are living, as well as my wife's paternal grandparents. So the little girl has a lot of grandparents & great-grandparents. To that end, to help her and future great-grandkids differentiate between all of them, I liked the idea of using more ethnically-appropriate terms of endearment for my dad's parents, since of all my family members they are they only ones who still use Polish language and traditions, and attend Polish National Catholic Churches (as well as my father and myself).
From what I understand the proper word is Dziadek, but like a lot of other US users on polishforums, the Polonia diminutive "Dziadzia" was used to refer to my father's grandfather, and he emigrated to the midwestern US from Ceranów in 1906.
Side note: my paternal great-grandmother was called "Busia" by her grandchildren, but unfortunately I read a lot of disparaging comments between Poles in Poland and Poles in America/elsewhere in another related thread a few years back regarding the etymology and use of the term - http://www.polishforums.com/language-17/spelling-aunt-8786/4/
. My paternal grandmother is a mix of mainly German & Irish with French & English as well, so a Polish/Polonia term didn't seem appropriate and I can avoid that debate. We'll probably either start calling her Oma (German) or Maimeó (Irish), depending on whichever she's more comfortable with for her great-grandchildren.