I used to work in, and owned my own business within, the active travel industry (it's been awhile) .

IMHO, you want to need to answer 6 items, which will help you find the right itinerary and tour operator for your needs (or at least winnow it down to a small list):

1. Region/Country
2. Type of activity (e.g. biking, running, hiking, cycling, paddling, walking)
3. Level of activity per day (all day, 1/2 days, hour or two).
4. Level of support (fully guided, partial support, logistical support only (aka self guided)).
5. Size of group (some operators focus on small intimate groups of 8-16, normally more expensive...while others take larger groups (up to 30ish)
6. Tour Budget (without airfare...99% of all active travel companies don't include airfare, which is good for us FTers).

Once you have that info dialed in, you can find the best operator, and like minded individuals, to fit your needs Most operators are also happy to do a private tour...you take all the slots on a given itinerary. With a private tour, they may give a price break and/or adjust the itinerary to better fit the group's needs.