All the Vanguard stuff (so far) seems to be from the "Vanguard Visionaries" series. The reviews of them on AMG are pretty dismal for the most part. One of the main complains being the lack of liner notes (which has no effect on eMusic DL's for that matter).
There's a Larry Coryell set which has some interesting stuff on it, but it's an odd selection. I'd MUCH rather get the full albums, but a few tunes worth getting are: "Stiff Neck", "The Jam with Albert" and "Spaces (Infinite)".
FWIW, there's a Country Joe & the Fish "Visionaries" set, too. Worth DL-ing "Not So Sweet Martha Lorraine" and "Masked Marauder", if nothing else. Maybe the "The Fish Cheer" for nostalgia purposes.