Tree removal is obvious. It has so many benefits for a relatively low cost. But as much as I would like to think so, architectural changes are probably a dubious expenditure of funds if the goal is to grow the membership.
I can't quite put my finger on how to do this, but I think the long term sustainabilty of many family clubs has to involve kids and wives. In other words, assume that the guy wants to join a golf club. What is going to make the WIFE want to join a particular club, because wives are increasingly part of the decision making process.
There is a tennis and swim club in a very nice suburb of NYC. It is owned by a family. They had a large number of tennis courts, platform tennis courts, a quaint old clubhouse, baseball field, and a lake for swimming and canoes and sailing. The owners decided to make very large capital improvements, assessed the members, and raised dues. They built an olympic size pool and a beautiful new clubhouse, complete with restaurant and bar, as well as an exercise facility.
They instantly lost many members, but within two years membership was full and now there is a waiting list. Why? Because if you are raising children in the towns that surround this club, your wife will want to join because that is where all of your kids' friends are hanging out all summer. Even guys paying dues to area country clubs with a golf course and a pool find themselves forking over the money to join here.
I can't help but think that many country clubs have to change their attitude to children on the golf course, find time to get kids playing, maybe even run summer camps that include tennis and swim team. Make it a place where Moms want to send their kids, and oh by the way, Dad can play golf there. It's not so much "build it and they will come" but rather, "change your attitude and they will come."
But since you mentioned the 18th hole
wouldn't it be cool to take out all the trees on the left as L & M built it, and let the bombers have a go at the green? Or would that be a safety issue with the hole on the left? The fairway bunkers on the left are a classic problem: they are far too close to the tee to be relevant for today's game, so they only catch the shorter hitters. Do you move them out or leave them alone? Good luck!