Joe,
Mario made some great suggestions; I have a couple to add as well.
Fleetwood Mac's BBC Sessions
The Vaudeville Years 2-disc set (which has alot of outtakes and full versions of tunes from "Then Play On"...such as the full 16+ minute version of "Underway", which is only about 3 minutes on TPO)
I'm looking forward to the new "Show Biz Blues" set (which I think is the actual title of the long-awaited Vaudeville Years Volume 2 set)
Although I think "End Of The Game" is a great album, its definitely an "acquired taste" in Peter's playing. Its not very accessible (maybe because after all these years, I'm finally hearing it with "sober" ears...if you know what I mean...
)
I HIGHLY recommend ALL of the Splinter Group material. You can really hear the rebirth of his playing from the first album to "Destiny Road". I can't wait to hear what's NEXT from Peter!