Traffic's Low Spark Of High Heeled Boys was/is a song that I'd listen to over and over again. (If I were to ever taked LSD, that would be the song I'd listen to).
That is a tough song. So much of the music from that time frame I've often wondered about how good it must really sound when high. I didn't find out that they did that song until this past summer.
I'd Love To Change The World by Ten Years After is another one in the same vein that seems like it would sound real good while "experimenting."
The beginning of Into The Void by Black Sabbath is mesmerising. Its just the most wicked of riffs. If I was a boxer, I'd want the beginning of that song to loop over and over again as I made my way to the ring.