The old timers give the young'ns tips on the 60s.

As I started reading your post I was thinking Moby Grape but you already found them. Try these:
Spirit - Twelve Dreams Of Dr. Sardonicus, it holds up very well.
It's A Beautiful Day - It's A Beautiful Day.
Chicago Transit Authority, it's the first Chicago album and is still a fantastic album. Great songs, one of the best guitar players of the 60s, just a perfect snapshot of the times.

Try this...

{http://www.elwp.com/Joe%20Cocker.html}

Of course when Joe wasn't on mind altering substances...he made some really good music..if just a bit of an acquired taste!

How about Spooky Tooth, Spooky Two is the cd you want.