Actually, Nate makes an excellent suggestion. What missions go unfulfilled now?
Only thing maybe to add to the survey is a question about price range for that "unfulfilled mission".
In other words, if you go get a C-130 for the folks saying they need more payload and nobody can afford to fuel it...
"If we added an aircraft capable of carrying four FAA sized adults and baggage, would you fly it regularly if it cost $X, $Y, or $Z?"
And of course you probably already have data on who's got certain numbers of hours and ratings, but if the insurer says a particular type needs say, "10 hours in type" you can ask that question in the survey also..."
"If you had to fly with a club CFI for 10 hours in this aircraft before you could rent it solo, would you pay the $X for that? Would having a temporary block time discount for those who want to meet the minimums be something you'd want?"
Etc etc etc.
It's been many many years since I played the role of club secretary and I still have the scars. We brought a Mooney on leaseback into a two airplane club back then and virtually nobody flew it because they didn't want to go get the 5 hours or whatever it was back then to meet the minimums. I did and pretty much enjoyed that airplane all to myself whenever I wanted to use it. Took it on multiple trips and never once had a scheduling conflict. The Doc who owned it was glad a few of us bothered to fly it.
So you have to think about that part also. People can be ultra lazy when presented with the option of, "I can rent the Skyhawk and go flying right now, or I can see if a club CFI is available, have to book them and their time as well as the airplane -- well the airplane is sitting so that part isn't a problem -- pay them the reduced rate they all agreed to charge for checkouts in the Mooney --and ... Ahh hell with it. I'll just call and book the Skyhawk and go flying..."
Back then I found the minimal price difference (in that particular club) between the 172 and 172RG also meant I could book nearly anytime and the Mooney was also cheap back then, so between the two retracts I always had something I could go fly "right now" and maybe even book to be gone a week in. The Skyhawk was nice but it was always a bear to book on weekends.
So in that particular club... We'd have added another Skyhawk or similar if we could have before the whole club folded for non-aviation reasons. Something with a "one flight" checkout (assuming the pilot wasn't out of currency or totally rusty).
Unfortunately the low end airplanes appeal the most to weekend warriors when it comes down to what actually flies.