Stevie Ray Vaughn is good, as is The Beatles, and the Who. Pink Floyd, CSNY, Bee Gees (Though i'm not sure they count as classic rock), Boston, Kansas, Chicago, Springsteen and the E steet band (Though Bruce hasn't been as good since "Born in the USA." After that he decided to be an "artist.").
The Rolling stones, man. Exile on Mainstreet may be the closest thing to a favorite album i've ever had.
I also intend to pick up the Traveling Wilbury's collection tonight. That's another great band.