[theorique]

Speaking as a man, if I were in a mixed group and addressed in various ways:

guys and girls - OK. Very casual.

ladies and gentlemen - OK. Somewhat more formal.

men and women - Weird. Sounds stilted.

boys and girls - OK, depending on tone. Would work better with an ironic tone when addressed to adults. Would sound stupid if expressed in kindergarten teacher tone.

ladies and boys - seems a bit forced. Also, it makes me think of "ladyboys" (e.g. transgendered Thai prostitutes)