I don't mind being close to people I know and like. I like cuddles and I like warmth, and, for me, being close without actually doing anything else is a great way to say I like you. It was also a really great way to get spontaneous backrubs out of my family when I was younger.... >.><.< I miss that. Now, I'm more uncomfortable with close because I don't know what it might mean to the other person, and I'm aware of that fact. And if I don't know a person, I'm not going to be all up in their space, and would prefer that they not be all up in mine either. In fact, if I don't know you and have no desire to get to know you, my thoughts run more along the line of Get off my lawn!
Elbow wars on planes are fun... :/
My main peeve with hugs is that I don't know where to put my arms. So you can hug me or I will hug you, but if we both go for hugs at the same time, things get awkward.
I do have a thing about people being behind me, especially if I don't know them or they're looking over my shoulder. I'd much rather if they were where I can see them or beside me. If they're behind me, I don't know them and they're looking over my shoulder, I'll just be a wreck of can't do anything, can't do anything, can't do anything. Thankfully, this does not happen often.
I also don't like people's hands or faces around my face and neck unless I initiated it. It makes me want to bite. I mean, they are conveniently close to my teeth and I don't know why they're even getting that close in the first place, so it'd serve them right. But society says biting is bad...