Hey, CynicalGabe!
I will refer by someone’s first name if I am initiating the conversation. Other than that, I don’t usually refer to people by name.
Coincidentally, I now work at the same school where I went to college. Being an adult and all, I feel free to call my colleagues by their first names, UNLESS they were my own personal professors. Out of habit, I still think of them as “Professor.” In addition, I also think there’s an element of respect, even though they are not my teachers now, I think it’s okay to recognize that they played this important role in my life. I realize it sounds a little weird when I walk into a meeting and say “Good morning Bob, Ann, Prof. Smith, Dave, Prof. Brown.” but I’m fairly confident that people “get it” (mostly because it comes up in conversation). I also address my own personal dean as Dean, but other deans by first name.
They gave you your own person dean? That is too cool!
in work if there are multiple daves i go with last names. it does seem strange to people… and i do get asked about it. with 7 eds in one office what are you gonna do?
I spent a lot of time in college causing trouble, they needed one whole dean to keep up with me. 
I’m with CynicalGabe. I have no idea why, but I always flinch inwardly when people call me by my given name. Either given name, actually. It just weirds me out for some reason. I flinch slightly less when people use my name to attract my attention, but using my name after you have my attention just irks me for some reason. It makes me not trust you.
Possibly because when I was growing up, my parents only called me by name if they were trying to get my attention or I was in trouble.
I used to have a similar habit when I was a teenager. If someone had shortened name or a weird nickname, I would do anything I could to avoid calling them by it. It was like I just couldn’t bring myself to call people things like “Toast”, "Yeti, “One-nut,” or even just plain-old “Steve.” I did a lot of “Hey!”-ing when I was younger.
Now, I don’t mind so much, but I call just about everyone by their full name. When I met Harborwolf, everyone called him “Dave.” I could never bring myself to do that, so I called him “David.” Now everyone calls him David.
What, didn’t you have a middle name? “Mama Jane Zappa, you come in here RIGHT NOW!!” 
- Being called my first name doesn’t bug me except when it’s one of those “salesbeings trying to get cozy” situations.
What’s funny is that to this day, I have trouble calling someone by name if they have the same first name as one of my parents. I grew up in a time where nobody called their parents by name, and somehow to this day there’s a mental block on both of those names. I manage to do it, but it feels very strange and disrespectful.l
I’m also uncomfortable using names, first or last. I find it very strange when someone I’m already talking to uses my name, unless it’s for emphasis like “Jane*, how could you!” or “Now, Jane, are you pulling my leg”. But if it’s just “How was your day, Jane” that’s kind of creepy, one on one.
I’m with Aangelica, it makes them seem less than trustworthy.
Ardred and I use pet names, usually ‘babe’, as in “hey babe, can you grab me a soda while you’re in there, please?”
Yeah, I do almost the same thing. The only difference is that it’s almost exclusively people with whom I am intimate or very close friends. Aquaintances, not so much, because I have to scream at them for spilling beer and sloppy joes on my carpet or setting my goddamn window on fire.
I was at a wedding a while back, sitting across from me and some friends was one guy’s Mom. I quietly asked my friend’s husband what his Mom’s last name was. (There was a divorce and I knew it was different his his.)
He said “oh just call her Hope.” (her first name) His wife who knew my Mother very well and I both gasped in horror and she said oh-no Mother-of-Goob would hurl a lightning bolt from Heaven if I used her first name.
Generally I use a name once when I say hello and vary rarely otherwise unless I need to specifically get someone’s attention.
When I interact with anyone holding a superior (or seemingly superior) position relative to me, or anyone who I do not know well, I take care to always address them as “Title Lastname” (With me, they tend to be professors), even in informal settings.
There’s a simple logic to it: I don’t care to be addressed by my first name alone, so why would I do so to other people?
I am a teacher, and teachers use last names more comfortably than most people, I think, simply because it’s the way most of the people we interact with on a daily basis identify us. Some of my students still don’t know my first name, though I don’t hide it particularly.
I call students by first name, last name, or nickname depending on how they are identifed by their peers or what they asked to be called. I use their names to call on them, to get their attention, and when I say “hello” when I see them in the hall or when they walk into my room. I do this because a lot of kids think that teachers don’t really differentiate between different students, and I want them to see that I do see them as individuals. I don’t think they think I’m creepy or untrustworthy (though I will cop to being seen as weird, for a variety of reasons)
Any fellow teacher is called Mr./Ms Lastname unless I know them well. This is for a combination of reasons–mostly becuase A) I’m still young and B) it’s how I think of them (since that’s how the kids talk about them).
I try to stay on a last-name basis with parents because it is a professional relationship, and it helps stop the bullying some of our parents are prone to.
Outside of work, the only times I use people’s names are to get their attention and to confirm who is on the phone–you know–“Hello!” “Hey! It’s me!” “Bob!”
Why impose your personal preference on other people? Why not simply call them what they prefer to be called? 
When I was younger, my aunts and uncles were all just called by their first names, so my aunt Joan was just Joan. (Probably that started because my youngest uncle is about two years older than my oldest cousin, so calling him Uncle Jay would have seemed silly.) About five years ago, right as I was hitting adulthood, some of my cousins started a movement within the family (there are seventy-four of us first cousins, plus spouses and fifty-some odd kids, so we’re big enough for a movement) to call aunts and uncles Aunt Joan and Uncle Jay. This kinda weirds me out, so I’ve stopped calling them anything if I don’t have to.