I think some people may be missing the point here.
When I enquired about a holiday I was interested in for this Autumn all the people on the trip were 60/70/80+ and I said 'no thanks' and went elsewhere.
Before accusing me of being ageist, please read on.
I have had approx. 10 holidays with JY and all bar one were very enjoyable. In the last few years I've had 3 excellent USA trips, the most recent (Florida) I'd describe as superb. I've been lucky enough to meet and enjoy the company of many people of all ages including people considerably older. These were mixed age groups and a persons age was irrelevant.
The one I didn't enjoy I was a similar age to the original poster on this thread and virtually all of the rest of the group were a great deal older.
One complication is the male / female ratio. I've been on a holiday with 4 men and 36 women, and I believe that is not uncommon
Now I'll make a guess - JY realise that their holidays would be improved, and of course more sold, if they had more younger people, more active people of all ages, and more men. Active holidays have been reintroduced for 2015, and I hope they are successful (especially as I have booked 2 of them already!).
JY holidays are good value well thought out trips, that for me are best enjoyed with a group of all ages and a good male / female ratio.
The response to the original post has been helpful from some emphasising how good mixed ages groups are, but less so from others as the holiday she mentions clearly is not a mixed age group. Calling her ageist for asking what for me is a perfectly reasonable question doesn't help.
Di, can I make a suggestion. JY is fortunate in that it has excellent travel advisers who I've always found to be very helpful. Why not phone them and talk things through to find the right holiday for you? There are some great holiday experiences awaiting - don't miss out.