btw, don't be afraid to call various tour companies and ask about the demographic of the typical groups on their tours. you may not get a specific (or honest) answer, but it's worth a try.

one thing to keep in mind with a longer tour (ie 3-4 weeks), especially an expensive one, is that typically, the folks who can afford that much time (and expense) will be older. not a lot of 20 & 30 year olds can afford to vacation for an entire month (or pay $6,000 for a vacation).

there are 100s of bicycle touring companies catering to a huge variety of demographics. find the one that fits your needs and interests.