Crossroad Blues - Robert Johnson
Patience - Guns N' Roses
Asilos Magdalena - The Mars Volta
Stairway To Heaven - Led Zeppelin
The Battle Of Evermore (I think its mandolin though) - Led Zeppelin
From the Beginning - Greg Lake - ELP
check it if you dont know it but it does get FM play so you probably have. You can find him playing it more recently on youtube at the Royale Palace if my memory is correct. He still sounds great. Just one of those songs that touched home for me.
Bet no one ever heard
Animal Skins - Crack the Sky - Animal Notes '76
an interestingly alternative kind of tune & guitar playing with a great message to the wealthy users
how about
Fires at Midnight - Tull - Songs from the Wood
I havent heard it in awhile it might not be the acoustic kind of thing your looking for, but an all time fav of mine
I like oodles of acoustic music, but as far as specifically the GUITAR PARTS of the songs being great, I have to mention:
Black Queen by Stephen Stills
Ambulance Blues by Neil Young
White Summer-Black Mountsainside by Led Zeppelin
everything on Bob Dylan's self-titled debut album