Whether puzzles are waning or not may be a function of where they're located (and this includes whether your area sees many traveling cachers). My area has a lot of puzzles, maybe too many. However, I don't have any data regarding how often they are found.
Personally, I am an engineer and will go after puzzles that are along science/engineering lines.
I do not spend any time on read-my-mind puzzles. Maybe it's right-brain vs. left-brain thing, but I don't do well at second-guessing what the CO had in mind. I'd rather spend the time finding caches or organizing the challenge caches that I'm working on.
Therefore, for me it's not an instant gratification thing. I don't do well at many puzzles and don't bother with them. But I put in a lot of time planning trips and targeting caches that will contribute to my stats or challenge caches.
Multis: I've been burned too many times with long multis that have a broken link somewhere. So for a while I avoided them totally. But recently I've restarted with multis that are of a shorter variety, like 4 WPs total. And, yes, that has resulted in some interesting finds and no complaints.
