Something has stuck with me for a long time, but for some reason it just popped back into my head and it got me into some deep thoughts on the matter. Many years back, I was talking to one of the older attorneys in my firm. I'd say she was in her late 50s or so. I referred to someone in the district clerk's office as a girl (e.g., "one of the girls in the office is pulling that for me") and she corrected me by saying "women, one of the women is working on it." I took her meaning. I guess it can comes across as ... belittling? chauvinistic? derogatory? something like that. I wouldn't say "one of the boys in the office is pulling that for me." I'd say "one of the guys..."
But "boys and girls" are the common word pairing. Same with "men and women" or "ladies and gentlemen." But for guys, I guess it's "guys and gals?" I would never say "one of the gals over there is helping me." That sounds way worse. In a formal setting, like if I was in court, I think I'd say "one of the women" but I'd still say "one of the guys" if referring to a man. I think "guys" is generally acceptable in both a casual and formal context. I can't picture myself ever saying "one of the men in the office," but that's technically the equivalent word.
Anyway, so my random thought on the matter: "Is there even a casual, female equivalent to "guys"? If not, is "girls" actually derogatory or offensive in every context when referring to an adult female?