I refer to my aunts and uncles as "Aunt/Uncle FirstName". This is standard in my family.
One exception to this, however, was me at one point. Most people in my family are adults when they first become aunts/uncles, but I was a pre-teen. For a few years, my sister's kids just called me by my first name.
Then, one day when I was well into my teens, one of them called me "Daydream," as usual, and my BIL responded to them with, "AUNT Daydream," and added something about how they should call me that out of respect.
I don't remember if my sister said anything in agreement, or if she was even in the room at the time. I also don't know if they'd discussed it beforehand. I remember wondering if the kids were going to resist using "Aunt Daydream," because they weren't used to it, or perhaps just forget to, but they didn't. The eldest is 30 now and they all still call me that.
It's a good thing I didn't mind being called "Aunt Daydream" since BIL didn't ask me!
The truth is, I had
noticed how the kids referred to his sisters as "Aunt FirstNames" and kind of wished I was referred to that way, too. But I never would have said anything at that age, or maybe ever. I just assumed no one felt I "deserved" it since I was young when my sister started having kids.
I don't know if it had always bothered BIL that his kids didn't address me that way, or if it suddenly bothered him because I'd become a young woman, but I really appreciated him doing that.
I don't think anyone in my family refers to non-relatives as Aunt or Uncle. Aside from teachers, I don't think I was ever told to refer to an adult as Mr. or Ms. as a child, either.
My parents' friends were just known to me by their first names, but as others have mentioned, I'm pretty sure I avoided calling them that to their face. If my mother's friend, Sally, was in our living room, I might have said to her, "Would you like something to drink?" Then I'd go into the kitchen where my mother was and say, "I'm getting some soda for Sally."