Elevetiquette
My office building is a modest four floors, and is equipped with not one, but two elevators.

I imagine in larger office buildings, the elevator traffic is much more dense, but the same set of rules which I am about to lay down certainly would apply.

First of all, there is a set walking distance from the elevator where one is expected to hold the door/have the door held. In my office building, I will hold the door for you if I a) you are several paces behind me, but I know you; b) see you coming through the door and you are within shouting distance for me to ask whether you're going up. A good general rule is if you make direct eye contact with a person coming through the door, you should probably hold the elevator for them.

Button pushing. My general rule is, if I get in first, I will press your floor button. If you get in first, please press my button. If I know what floor you're going to, I'll press it for you. (With only four floors, two of them occupied by my company, I do this pretty often.)

Once inside the elevator, there are boundaries. I will take up space in a back corner. With one other passenger, they should take the opposite diagonal corner. If a third enters, passenger #2 should step into the back corner opposite me, leaving passenger #3 in a front corner. If there are more than three people in the elevator, please observe the rules of personal space.

Conversation. With such a short ride, I don't expect it, nor in the morning, do I want it. If you talk to me, I'll answer, but I'm not going to ask you how the weather is.

Last but not least, if you are in the elevator and you are cleaning it in the middle of the day (we have the cleanest elevator in the WORLD), please do not try and hold a conversation with my boobs.