The individual finds don't usually excite me much. The really interesting part is correlating the results of 35 years of research, along with what others are finding. That's when the real discoveries are made. Then you begin to get a picture of how the early cultures arrived, developed, reacted to climate changes and other incoming groups, and finally how they reacted to the European conquest.
Putting all of that together is what I like. Of course, going out and playing in the dirt on a nice sunny day is hard to beat!
I was reading recently that apparently cold temperatures can affect the cranium size in a population. I was surprised, if it's true.