(I quoted the OP because I want to remind myself what the actual question is: “What behaviors do you see or how does it change the dynamic of the office?” I feel like in the responses the question has sort of morphed into “Are you a dick to her, or do you treat her normally?”, but I’m trying to answer the original question.)
I’m a woman who works in a male-dominated field. Not trying to call myself “stunning,” but when the field is mostly male, being a female who cares about your appearance is enough to at least put you in the “attractive” category.
A month or two ago, I was having dinner with a friend from an old job, one who was rather obviously more accommodating and helpful to me than he was to the average employee, and who freely admitted he was attracted to me. I was explaining to him how I sometimes felt self-conscious as a woman, and thought that people might think of me as less intelligent or competent as a result. I mentioned some specific examples.
I told him about a conversation between me, my manager (a male), and another guy, and how the other guy seemed to be facing and talking exclusively to my manager, as though I weren’t there and didn’t understand anything that was going on. My friend said “Or maybe you’re just an attractive woman and he’s an awkward nerd and isn’t sure how to act around you, did you ever think of that?” I found it comforting, to think that his behavior might not be due to a presumption of incompetence but simply due to being nervous around a woman.
Another anecdote: I was working on an issue with a male coworker (who has sometimes seemed more eager to help me out than he would to help out other coworkers). While he and I were sitting at the computer together, a couple other (male) coworkers approached me to talk to me about a different issue I was having, and tried to help me troubleshoot that issue. My first coworker quietly remarked to me about how people sure seem eager to help me, and they never seem so eager to help him.
I do also sometimes feel like if I walk into a room or walk down a hall, that men will look up and let their gaze linger longer than if I were a man (or than if they were a woman).
In summary: Many people don’t act any differently. Some people seem uncomfortable to be around me and want to avoid eye contact. Some people seem extra inclined to want to help me. But you could probably account for some of that difference simply by whether or not the person likes me. On my end of things, I’m more inclined to want to help some people than others, and I’m also more inclined to try to shorten conversations with certain people, and that’s not based on how attracted I am to them, but how much I like them, as a coworker and as a person.