Wow, lots of my favorites already mentioned, and I'll try to avoid duplication:
Workingman's Dead--Grateful Dead
Phases and Stages--Willie Nelson
We're Only in it for the Money--Zappa/Mothers
After the Gold Rush--Neil Young
Who Knows Where the Time Goes--Judy Collins
Lyle Lovett and His Large Band
Giant Steps--John Coltrane
The Inner Mounting Flame--Mahavishnu Orchestra
Aurora--Jean-luc Ponty
The Yes Album
Live in New York--Nirvana
Crosby, Stills & Nash (1st LP)