I never use Instrument Tracks, just don't trust them, I don't know why. Maybe it is because there are lot of restrictions with them, and I find separate Audio-Midi tracks more logical.
As for screen area, there are Track Folders for saving it. And this why Nested Folders feature is absolutely required, to keep pairs (or more) of Audio-Midi tracks in separate folders, and to group this "instrument" folders in bigger folders such as Drums, Synths, Pads or Verse, Chorus, etc... I hope it will be the next big improvement after Track-To-Track Routing.