I didn't think I'd ever use one but after trying Chord Track I was surprised how it can be an effective tool for songwriting.
One included in SONAR, not 3rd party would be welcome.

+alot, this would be most welcome.

+1.   An option to choose from several different voicing for each chord would be cool. Random voicing too.

Afrodrum
+1.   An option to choose from several different voicing for each chord would be cool. 

That would indeed be nice, also to have a button/command to change voicings on the fly.

I would like to see a chord track in Sonar Platinum similar to the one in Cubase.  You just select the chord you want your keyboard to follow in the chord track and the chord track will automatically play the correct chord.  This is very helpful for us guitar players, who are not really proficient on the keyboard.

..and it would simplify if this also came as ability to include in staff view, and chords are there from start.
So diagrams of chords included really useful.
 
But as Artist user I cannot vote for Platinum only features of course.
 

I really want this feature in Sonar Platinum.  Please make it so Cakewalk.

In the meantime perhaps Toontrack's EZKeys would be of benefit. That's how I use it.

+1 Would love to really see this in Sonar.  If they can integrate this perfectly with MIDI, and auditioning notes, this will be amazing.

voted!