Harder to find, in my experience, and far more apt to stick with you, year in, year out.

I agree--speak up about your feelings, but if they aren't reciprocated, let them pass, as feelings nearly always do in time.

One more thing to keep in mind. Romance may hang on timing. If you manage to have that awkward conversation when your friend is getting over a break-up and ready to move on, you're far more likely to get the response you're hoping for than when they're in the throes of a new infatuation.