If everyone I dated were in a room, then I, a heterosexual male, very much might address that room as guys. As in, "hey guys, what are you doing here?"
It's an interesting bit of context. I also grew up with guys as a generic plural, but it's not really generic, rather it's a mixed group plural. It would feel just as natural to say "the people I date", as "the women I date", but never "the guys I date.
Even that's a weak rule though. For example if a girls soccer team performed really well you might hear someone say "those guys really gave it their all today" (though I'd say this usage is mostly dead, I don't think I've heard it this way in a long time), but never "THE guys really gave it their all today".
I'm sure some linguists have studied this and have a term for this kind of thing.
I absolutely would not say "hey ladies"
It would feel too formal to say "hey everyone"
"Hey people" would be awkward
"Hey you all" eh
It might be better to leave it at "hey"
It might be best to just say "bye"