Since 2006. If there's a neat place, cave, waterfall, view, old cabin, graveyard, rest stop....there's a geocache placed at it. Great fun when you vacation in a new place....use geocaches to find the real cool stuff not in the tourist brochures. You will absolutely find new riding areas and trails....along with a bunch of cool spots and cool things right closeby that you never knew were there.
Like semi-serious photography, it's not really something you can 'fit in' while out with a group, unless everyone's doing it; you'll hold people up and not have fun.
Had lots of good days where I went out alone with no other plans but to do a series of caches on the bike, quad, or feet. A series is fun because it leads you around a trail network or something similar.
Don't fall into the trap that a lot of new people do...find a few, then feel that you have to put some out yourself. After you find 100 or so, you'll have a much better idea of what makes a good, fun-to-find cache....rather than putting out something crappy, in a crappy container that breaks or fills with water in 5 days.
I don't have a super high find-count, but I usually only do caches that are outside the city, in the woods, on trails, etc.
I used to carry around trade items, but it wasn't long before I didn't even bother trading...just liked it taking me somewhere..find the cache, sign the log. Kids, however, go insane for it. Imagine a kid using a handheld electronic device that leads them to an ammo can jammed full of toys hidden in the woods. Best...day...ever!! But, people are assholes, so make the kiddies wait for you to open the cache...I've found porn, knives, weed, and one that someone thought it would funny to take a crap in. But those were all ones that were in populated areas and found by non-cachers. Usually the more remote a cache is, the better it is...hiders will put the cost and effort into a cache that they're pretty sure isn't going to get muggled.
No need to wait until next riding season...caches are tagged with attributes, so set the 'winter-friendly' flag when you search, and you'll have lots that are high enough or sheltered enough to be able to hunt and find during winter.