My mom's sister is just Aunt, and my mom is just Aunt to her four nieces and nephews.
I call my dad's sisters by their first names only. When I was younger, I'd say Auntie Doreen if I wanted her to do my nails (she's a cosmetologist). I might've said Aunt Denise at some point, but I don't recall.
All of my dad's nieces and nephews use the Aunt and Uncle titles for both of my parents. Most of them end up saying Unca Dave, though, because that's how my oldest cousin said it.
My mom's great nephews call her Aunt Robin, because as is tradition, their mother's sister is just Aunt. Luckily it evened out that my Aunt had two sons and two daughters, so the daughters' kids will just have one Aunt. Actually, my one cousin doesn't like to call my mother anything; last time we saw him, he told my mom that she wasn't his friend. He's six.
My one cousin's husband is named Dave, as is my dad, which created an interesting dilemma on what her nephew should call them. It turned out that my cousin's husband is Uncle Dave and my dad is Uncle David, because most of my mom's family calls him David.
I always used the titles Aunt & Uncle for my great aunt & uncle.