Changed guitar strings

I changed strings on the Alvarez/Yairi yesterday. I'd been meaning to for several weeks because they haven't sounded good at all. This is one of the shortest times between changing that I can remember. I had tried the Martin Lifespan SP strings - I put them on on Nov. 17, 2010 - and they already sounded like crap. That's what I've always had against Martin strings - they sound great at first, but they just don't last very long. So I went back to the Elixir 'nanoweb' custom lights (.011-.052). I've never been thrilled with their sound, but they last a good long time. I also bought a cheap set of D'Addario's just to keep on hand.