Ensemble Music - what to play?

Sarah left a message on our newsfeed today asking for suggestions for music for a flute group she is planning to set up. By coincidence, today I've been trying to sort out music for our course at Purcell and also in Croatia. I always plan too much. It is really tricky choosing material that covers all the varying standards that we have on courses.
I have the most enormous collection of ensemble music, a great deal of which has never been played. As I was sorting through the collection, I had the thought, "Why do I always look for something different?" I do try to do new things, but over the years some pieces have been played again and again. These include:

• Walk Like This: Ian Clarke
• My Dog Pooh: Isaacson
• Gypsy Airs
• Cossack Ride
• Little Red Monkey: Jordan
• Big Day: Mike Mower
• Folk Song Medley: Mike Mower
• The Flutewise Theme: Gareth McLearnon
• Suite: Steele

Actually there aren't that many that have had repeated playings (I can tell the ones that have by their tatty covers). That got me thinking why? Many of our current course members won't have played any of the above, but older course members will remember them. If someone comes to a course once a year, I wonder if they would mind playing the same piece again. After all, they can always play a different part. Familiarity also makes us quite comfortable. Maybe it's te staff who need to explore new material.
Any comments would be welcome.