I've owned 'Memories:The 68 Comeback Special' two cd set for a couple of years now, but had no idea RCA put out a four cd set last August that has both sitdown/standup shows complete, plus both rehearsals.
I immediately bought it, and I gotta say that even if you're not an Elvis completist or obsessive, the big set is worth owning. I'd put the comeback special as one of the three or four greatest moments evah in popular music, and - unlike some albums where every new scrap makes the original seem less, not more - the expanded album is just better.
s.