jg0001, I think I can help you. To the casual observer, the shooting sports look pretty much the same: a target is tossed and it's either broken, or not. Yet, the games are quite different. Skeet and clays and 5-stand demand a more dynamic shooting style where trap requires more precision. Consequently, you'll generally see an older crowd shooting trap.
There's the economic factor. This applies to the shooter as well as the gun club. Trap is the most economical facility to provide since it requires only one machine and less land area. Think of sporting clays as golf with a shotgun -- a nice sporting clays facility represents a considerable investment and the shooting fees will be higher, per target, than trap and Skeet.
There's also the equipment factor. For shooting simple trap singles, almost any gun gun can be adapted and you don't need a gun that will provide a quick second shot. Trap is the only game where the pump shooter won't be disadvantaged. For the other sports, O/U guns are pretty standard. You can use an auto-loader for Skeet; however, for clays or 5-stand you'll probably want an O/U to give you the ability to shoot different chokes. For competition Skeet, you'll need to shoot four gauges (.410, 28, 20 and 12), this is an added expense.
There's also the social aspect. Skeet and clays are shot as teams with each member shooting in sequence with the support of the others. Trap and 5-stand are shot five abreast with little interaction between the shooters. Because of this, Skeet and clays are shot at a more leisurely pace than 5-stand and trap. Consequently, there's a lot more social interaction between Skeet and clays shooters. I've seen trap and 5-stand squads shoot a 100 targets with very interaction between the shooters -- it's an every man for himself kind of attitude. With Skeet and clays it more of a team effort. Five-stand may appeal to the younger shooters, with Skeet and clays to a little older and affluent shooters.
For most folks, it doesn't take too long for the new shooter to find out which of the games is best suited to his shooting abilities and personality.
Hope this helps.