Sandra, two mixtes is NOT too many. (I have four, but two will eventually be given away, I swear.) You need one for going fast(ish) and one for running errands. One with upright bars and one with drop bars or similar. Maybe one with gears, one without? Although now we're talking crazy talk.

My husband said I should warn you if you use a Brooks saddle that a women's Brooks with that Kalloy post still winds up with almost no adjustability, because the clamp is almost as big as the usable part of the rails. And a men's Brooks isn't much better.