I've been caching for a while and have satisfied most of the statistic-based goals one can attain. I have a full 366 day calendar, I've streaked as long as I felt I needed to streak (only lasted 102 days), my D/T grid is full three times over, and I've found more than enough caches in one day (100 was too many; never again). At some point I need to finally get to a May 2000 hide to kill off my Jasmer grid, but otherwise, I'm pretty happy with my numbers.
Since I am guaranteed to move around every two years or so, I make it a point to focus on geographic challenges. We started caching in Germany, so before I left I made sure we had a find in all 16 Bundeslaender, but that wasn't for a challenge. I did, however, qualify for Die Kurpfalz-Challenge, GC18EX3, which I quite enjoyed. So with each new move, my goal has been to complete county and Delorme challenges where I can: Virginia, Alabama, Olkahoma, New Mexico, and now Maryland and Delaware. And even when it's not for a challenge, I enjoy filling in new spots on the map.
I also enjoy celebrating milestones in new locations. We found our 4000th cache in Japan and our 6000th in South Korea. So this year, I was excited to celebrate our 8000th find* in the British Virgin Islands. I'm not yet sure where our 10,000th find will be, but I plan to enjoy it, and to take my time caching our way there.
*Well, it's supposed to be our 8000th find. Since project-gc still doesn't calculate milestones using lab caches, according to this site, it was our 7990th find. But hopefully that functionality will be added at some point.