an addition to the whole elixer debate. i used to use nothing but dean markleys on my acoustic, and they sounded great, but once, and only once, the salesman at the music store convinced me to try something else, so i did. put on the elixer polywebs 13-53. a year and two months later, i still wasn't planning on getting new strings anytime soon. they just sounded amazing. i broke one, though, so gave in and bought a new set.
scary part...the new ones sounded identical to the set i had just pulled off, proving that they do hold their tone for a crapload of a long time compared to other strings i've played on. i beat the hell out of my acoustic when i play, too. bends on high action as far as a major third, when strumming, i rival the volume (sometimes beat it) of a decent practice amp, and playing from open string up to the 15th (i'd go farther like i do on electic, but it's not a cutaway...). so these strings have pretty much sold me for life, now.