Hi qwertygirl, welcome to the forum :)
In my experience the typical age range is 40 plus, with most between 50 and 70, however there will usually be some who are younger and older than this. The trips I have gone on have had a varied age range and I personally think this adds to the trip. You are certainly not too old in your 50's.
I'm a very youthful looking 48 :rolleyes:
Get booking qwerty and have fun :thumbup:
Julian