Another way I've heard to diagnose it is if you have pain or soreness in the front of your knees, you're probably too low, and if you have pain in the back, too high. Though hopefully riding is painless, I sometimes notice my knees getting a little sore in the corresponding area if I ride a saddle that's too low/high. I go for my knees just a little less than fully extended, but pretty close, and I like to set the front end off of that for a big seat to bar drop, because that's what I find comfortable and fast. The almost-fully-extended is a good starting point, and it shouldn't be hard to adjust it from there to where you're really comfortable. Once you hit it, it's great- I've hesitated to move from road drops to bullhorns because my Langster feels so good right now. In fact, I'm going to go ride it right now.