When we went through a similar thing about 18 months ago we did not mention age either - worked on the principle that 18-25 year olds would not want to play 'Classic Rock' - seemed to be reflected in the response that we got from the advert.
Sounds like our band has similar aims - play Classic tunes and having some fun about once or twice a month. From playing pubs etc I'd say that it doesn't matter if you are male/female etc - audience like hearing the good old songs and singing along. We have a lot of debate around playing 'stuff that we like' v 'songs that the audience expect to hear' - I'd come down in favour of the latter - if you play an obscure album track by (e.g.) Bad Company that the drummer really likes, but the audience has never heard of, the reaction will be WTF?????? Play stuff like Highway to Hell, Alright Now etc and it does down a storm!!
Good luck with the ad
Mike