Can't believe no one's suggested getting your bike fit to you, yet.

Please, please, please: visit a pro bike fitter and get your saddle, cleats and bars checked. It might sound ridiculous to spend several hours and pay some dude $150 to shift your saddle, seatpost & cleats, backward or forward a centimeter, but those things make such a colossal difference.

If you're in the LA area, Nate Loyal is a great one to see. I felt a little silly walking out of the shop after paying him that much money, and the end-result (that day at least) was that he shifted my saddle forward about a centimeter and a half and my cleats back just under a centimeter, but the results were astounding--better than Dura Ace carbon aero wheels.

And after you've done that, consider buying a saddle from an LBS with a 30-day exchange program. I later bought a power meter and aero wheels, and both were terrific boons to my riding, but they pale in comparison to the fitting and saddle changes I've made this year.