Ladies does usually sound awful. I rarely make a point of countering with women though, as it sounds bolshy at the time but it is what I'd use naturally... except that I do use ladies, with women who I think expect it and would be offended if I used women!
Generally, I think ladies is appropriate if you are addressing people who you'd address individually as 'Mrs X' or 'Miss Y' rather than their first names. Generally older women or in a formal situation.
Otherwise it makes the speaker sound uncomfortable with women as people, so placing a barrier of formality, comic formality, or faux respect (which can actually be either smarmy, leery or insulting) between them and the women they're addressing, to distance themselves.
I'm afraid 'boys and ladies' falls into one of those categories. It sounds as though you're comfortable and jokey with you male friends but see the women as 'other', as a group, not as real friends. I say sounds like because I expect it's habit and you'll tell me they'd rather be called ladies and address each other that way (plenty do).
Other women, like me, will hear it as distancing and as a restrictive definiton conveying an expectation of 'nice' unchallenging behaviour.
Being called a lady always gives me a childish urge to behave in a very unladylike way - because I'm not a lady in the titled sense and haven't signed up to any code of restrictive 'ladylike' behaviour and I'm not going to accept you trying to impose one upon me. I'm a fairly kind and well-mannered woman though, so I usually don't.