I've already posted my take on what I'd love to see:
My ideal mix:
Disc 1 - Closet Mix
Disc 2 - Valentin Mix
Spread the mono 7" mixes & other alternate mixes (from Moe's oft bootlegged acetate) across both discs
Disc 3 - "The Lost 4th Album"
Using the previously unreleased rough mixes, not the 1980s remix
Disc 4 - Outtakes, demos & lost songs
Hopefully this could be a final outlet for studio or demo versions of lost VU songs like 'Lonely Saturday Night', 'Just Too Much' 'Sweet Bonnie Brown', 'Over You', 'Follow The Leader', 'If I Tell You', 'Sweet and 20' and the fabled 'Lonesome Cowboy' (not the same one on Loaded).
Discs 5 & 6 - Live at the Boston Tea Party
Rather than go for the existing Live 1969 shows (save that for another box set!), roll out 2 shows from their legendary times at the BTP! These were readied for the abandoned Bootleg series so it seems more than likely these will be a goer. They were leaked a few years back and man, the upgrade in sound is astonishing. I'd go for the Guitar Amp tape. For all its faults (the vocals are buried), the sound is gigantic and is the best representation of the band frenetic live sound that year.