This won't directly answer your question, sorry, but it is relevant to your question I think.
Tigerman and Memories are all you need for the complete sit-down shows, in the best sound quality, in my opinion. I believe they are complete, unedited, and of the best quality found anywhere.
For the Stand-up shows, the versions on Memories and Burbank '68 have the best sound quality, but unfortunately they are heavily edited with selections from both shows spliced together on both CDs, portions missing, and overdubbed applause in places. Therefore, the original NBC TV Special CD and Silver Box (Elvis Aron Presley) and the Lightyear '68 comeback special official DVD are essential in obtaining a more complete version of the standup shows in the best sound quality. For the parts of the standup shows that aren't officially released, as far as I know the COMPLETE BURBANK SESSIONS VOL. 2 is the place to get the rest, although portions of these shows were apparently not recorded, because the video tape machines were shut off when things went bad, so we may never get to hear the complete version of "One Night" from the first standup show, and the TV cameras were also switched off during Elvis' voiceovers of the Trouble/Guitarman portion of the standup shows a couple of times.
Now, regarding the studio material, I like what the official Memories CD has to offer in terms of the masters, but some purists won't like the fact that they are remixed, so again the NBC TV Special CD is a good buy. And, there have been a few outtakes, i think on last year's TT&F box. I haven't studied whether or not there are more studio outtakes, so I'll let someone else address that. Was there something on one of the Legendary Performer series?
There are alleged instrumental versions of If I Can Dream, which is supposed to be the backing track Elvis sung to in the white suit, but if you listen closely, you can hear his studio vocal in there very quiet, so my guess, although I can't prove it, is that someone simply ran the stereo master through the so called Out Of Phase Stereo (OOPS) process to eliminate the vocal (karaoke machine), so I do not consider that an essential one to get.
Regarding the two sit-down rehearsals, I think the CD entitled "COMPLETE DRESSING ROOM SESSION" has these in their entirety, unfortunately they believed BMG's typo on the Burbank '68 CD and messed up the running order just to put one track at the end allegedly recorded on the 26th, which never happened.
Also, Elvis did voice overs on a handful of takes of If I Can Dream, Trouble, Guitar Man, etc and I have these all on video, but haven't got them on CD. Platinum and Memories have a couple of these If I Can Dream voice overs if I remember correctly.
Sorry I don't have a tidy list of all this stuff, but I'd be happy to help you sort it all out offline if you want to email me. Or maybe someone that has already figured it out can let you know. Also, Much of this info is on http://www.elvisrecordings.com
Hope this helps.