Many aero clubs use 119.1 as both a base and air to air. I think you will find it is not otherwise allocated. You will have a significant audience on 123.45 remember!
There are a number of other "un-allocated" frequencies that one might use, but if you do, make sure that whatever frequency you decide on, DO NOT mention the frequency you are going to use on another frequency, as it wont be "private" any more!! Just say "go company" or somesuch. Safe flying.
