For a sixties sampler just south of mainstream I usually go to
Youngbloods first three albums
http://www.youtube.com/watch?v=3eDAN...pcTZjtehoDOU0Y
Moby Grape
http://youtu.be/sIeSb7dpdDw
Cream
http://youtu.be/J1PTrgww3lE
Airplane
http://youtu.be/e4AAYc7DrJg
Van Morrison
http://youtu.be/_2qr5EP74zk
Jerry Jeff Walker, John Hammond, The Dead, Janis, Jimi, Neil Young, not obscure but always takes me back to the planet I came from for a brief visit.
I love the obscure stuff (especially 50's & 60's garage bands) too but I save that for when it's time to get guests to go home (increasing the volume helps too).