I bought a double road bike while I was living in New Jersey (where it's flat). I moved to PA and regreted it because here it's hilly. I took my bike shop into a nice shop near AG, and to switch to a triple would have required a new crank (of course), bottom bracket, derailler and shifter. $$$

I went compact. And guess what? The shop put on a crank and cassette combo that actually gives me virtually the same gear range that a triple would have -- the top top gearing is MORE than I would have had with the triple. Plus no hassle of three chains in the front means less shifting for the rings and not having to worry as much about cross chaining. All in all it's a good thing. I had thought I'd buy a tri bike eventually with a triple, but now I think a compact double will be perfect.