Colour labels for tracks. A feature I would find really useful in Premiere would be to assign a colour label to various tracks.
I'm a bit of an obsessive when it comes to keeping my sequences in order and since I do a lot of work with different media formats as well as working alongside lots of different industry creatives involving VFX, animation, live action, documentary and drama workflows it's crucial that I can manage all of that in the edit. So when it comes to organising all the layers of audio and video it would be really useful to be able to select a colour, much like After Effects, and assign it to the different tracks so you can easily keep track of what should be where.
I know this might look a bit ridiculous but I made this mock up to help illustrate my point.