If I had a lot of down time to work on my bike, I would focus on bearings. After seening first hand the damage a failed wheel bearing can do, I try to stay on top of these things. In fact, I just revitalized one that seized up on me tonight so I can go riding tomorrow (and not be going through mud puddles this time). I take an o-ring pick and pop the outer seal off. Then, I use compressed air to blow what remains of the grease out (not much, usually). I pack the bearing with fresh grease and reassemble. Afterwards, they're good as new. I caught the bad bearing while changing my tire. I check the wheel bearings every time the wheel is off. Swingarm bearings are another one to look at. Most of mine had no grease in them and were corroding badly. I caught the problem before any damage was done. I'll be checking those more often.