I think that all of the Original Series films could stand to have some restorative work done on them - and I mean that in the sense of cleaning up any imperfections in the sound or picture. The dreary flutering Paramount logo over the intro of the films alone deserves to be replaced.
TNG should be completely redone. Take the existing 35mm negs, transfer them directly to high def, and then re-do the FX note-for-note on CGI. Screw the transferred-to-video crap that we have had for the show since its inception. I can only imagine the likely startling
look that the live-action footage alone would have. I remember the '97 remasters for TOS, and hoping that the same would be done for TNG somewhere down the line.