I agree that puzzle caches will usually not get as many visitors as a normal cache would in the same location. Unless of course the cache reportedly has great prizes or lots of money to find! I find the harder the puzzle, the greater the reward (both personally and monetarily). Supposedly, the Eye of Horus puzzle cache (waypoint GCQTGQ) actually has money in it for the first several finders. Money is a great incentive to find a cache...even to those who don't usually work on puzzle caches.
So if you make a puzzle cache, consider making the cacher's effort worth their while.