I tell you what I would like to see.
A dockable form dedicated to just input and output routing (and other routing). Maybe have a show/hide tickbox option to show the plugins within.

The current method of selecting Input/output routing (etc) can continue as per usual, this is in addition.

It would be VERY useful to see all the routing at a glance, on one screen, without all the other information in the way. Call it an editable summary screen.

streckfus
The advantage would be for those of us who don't like the separation between tracks/busses.  For example, I like to keep the number of busses fairly minimal: instrument groups (drums, guitars, vox, mixbus, reverb, etc.).  Since the bottom mic and top mic both contribute to the snare sound, it would be nice to have a main "Snare" track right there next to the top/bottom mic tracks in the track view.  Or if I want to do parallel compression in a track, I can route the source signal to a track right next to it.  When the track count increases, side-scrolling the separate track/bus sections gets a little tedious.
 
There have been a few requests for giving users the option to move tracks/busses freely as opposed to having them "locked" inside individual panes, so I think (for those of us interested in such a thing) our thought process was that track-to-track routing would allow for an "aux" track of sorts, thereby allowing us to organize tracks/busses as we like.
 
So functionally there's nothing wrong with Sonar's existing track/bus structure.  We certainly can route tracks to busses, busses to busses, etc. to our heart's content, but it can get a bit unorganized, especially when we prefer to organize/group busses in the way I described.  So yeah, more of a convenience thing than a "problem" with the way Sonar currently works.
 
I imagine creating an option to select "Tracks & Busses - One Pane" or "Tracks & Busses - Separate Panes" would probably require a major UI overhaul, and for those who like the setup as is, it doesn't make sense to get rid of the separate track/bus panes altogether, which is why when I saw "Track-to-Track Routing" as an upcoming feature I was seeing it as a way to, in essence, use an audio track as a bus, kind of a hack for those of us who'd like to be able to move tracks/busses freely within a single console pane.
 
I totally get the ability to record/print a synth, track, etc. without having to bounce it, so it'll be a nice feature regardless.  But I initially saw this as a clever way to bypass the limitation of having tracks/busses in separate panes.
 
I did see in an earlier thread about using a plugin with a sidechain input to effectively turn a track into a bus so perhaps I'll look more closely at that.  Or perhaps I'll submit a feature request to allow users to determine whether tracks/busses are organized in separate panes or move tracks/busses freely between panes, but that would require a pretty big overhaul behind the scenes, wouldn't it?  I'd think being able to send a signal from one audio track to another would be a bit less daunting...but I'm no developer so what do I know. :)

Thanks for your well thought out response. Indeed patch points would allow you to work exclusively in the track pane if you choose to do so. Tracks are actually a superset of buses in SONAR so there is no reason why you couldn't route one track to another aux track via a patchpoint and do your mixing there if thats what you prefer.
Something like this:
Track 1 ------\
Track 2 ------ Patchpoint 1 ---- Aux Track ---> Master
Track 3 ------/
 
The patchpoint is essentially a summing stage and routing point. Its a subset of a bus without the prochannel and fx processing and automation so its very lightweight. Sidechains in SONAR use a somewhat similar design but with a hidden sidechain bus that handles the summing of inputs prior to the plugin. The internal signal flow of Patchpoints is more complicated however since they have to act as track sources to integrate with recording, track UI etc.
 

Noel Borthwick [Cakewalk]
The patchpoint is essentially a summing stage and routing point. Its a subset of a bus without the prochannel and fx processing and automation so its very lightweight. Sidechains in SONAR use a somewhat similar design but with a hidden sidechain bus that handles the summing of inputs prior to the plugin. The internal signal flow of Patchpoints is more complicated however since they have to act as track sources to integrate with recording, track UI etc.

 
Very illuminating, Noel. I see where you're going with this...
 

Noel Borthwick [Cakewalk]
 
Thanks for your well thought out response. Indeed patch points would allow you to work exclusively in the track pane if you choose to do so. Tracks are actually a superset of buses in SONAR so there is no reason why you couldn't route one track to another aux track via a patchpoint and do your mixing there if thats what you prefer.
Something like this:
Track 1 ------\
Track 2 ------ Patchpoint 1 ---- Aux Track ---> Master
Track 3 ------/
 
The patchpoint is essentially a summing stage and routing point. Its a subset of a bus without the prochannel and fx processing and automation so its very lightweight. Sidechains in SONAR use a somewhat similar design but with a hidden sidechain bus that handles the summing of inputs prior to the plugin. The internal signal flow of Patchpoints is more complicated however since they have to act as track sources to integrate with recording, track UI etc.

I think perhaps I'm catching on now.  So in your above example, Tracks 1, 2 and 3 would be routed to the Aux Track via the upcoming Patchpoint feature, and that Aux track could then be used as a group fader for all three tracks just like a bus, or an EQ could be placed on the Aux Track to process Tracks 1, 2 and 3 as a group?  And I assume that Aux Track could then feed yet another Aux Track via the Patchpoint for parallel processing, etc.?
 
And each Aux Track (just like any other audio track, since that's essentially what the patchpoint is feeding) could be routed to any bus via the track output or through a send?
 
Not that I'd necessarily plan to route a ton of tracks together in series like that; I'd envision mostly using it to group similar tracks together so I could use a single fader or apply effects to the group while still staying within the track pane.
 
(I actually set up a fake session for visual reference but I couldn't post the screenshot, so hopefully what I wrote makes at least some sense!)
 
In any case, this does look like it'll open up a lot of doors.  Really looking forward to seeing this in action.

Yes all of the above. To clarify, the term Aux track is used functionally. There is no special aux track type - you can use any track as an aux. To route that aux to another track you would use a different patchpoint - eg Patchpoint 2.
 
Track 1 ------\
Track 2 ------ Patchpoint 1 ---- Aux Track ---> Patchpoint 2 ---- Aux Track 2 ---> Master
Track 3 ------/
 
And so on..

Yep, understood that "aux" is really just another audio track, but functions as an aux when using the patchpoint feature.
 
I'm thinking this feature is gonna be a real winner, and will make several others quite giddy. :)
 
Thanks for the feedback and clarification on the track-to-track routing.  Looking forward to it!

 
I quite agree with Beepster who says "Honestly I don't really like the workflow of having all my busses mixed in with my track strips (that's just me). Too messy and confusing."
 
My reason for desiring track-to-track routing was highlighted when I was using the harmony generation function of iZotope Nectar2.  I put it on a bus and then used a volume envelope on the bus to control when the harmonies would be heard in the Master bus. The harmony bus was driven by a send from a single 'normal' track. 
 
In my workflow I have a central screen that exclusively displays a console view of busses, and below that, another central screen on which I keep the track view. I prefer to have envelopes on tracks and leave my busses static (unvarying). The clumsiness appears when I have to go to the bus view in order to manage the envelope.     

Present Track - Bus also works fine ... only if the separator between the Tracks and the Bus can be widen as per users choice would be nice and if we can choose a color to make it more prominent would be nicer.
If the Track numbers are more then there is a very thin frame between Tracks and BUS

What's nice about the upcoming feature is that it allows those who prefer the existing bus/track structure to use it exactly as is, while it also makes it more flexible for those who'd prefer to have some bus-like functionally within the track view.  (And for the record, I personally wouldn't want all of my busses mixed in with tracks, just some that - for me - would be more efficient living right next to the tracks they're processing as opposed to in another pane.

GaryMedia
 
I quite agree with Beepster who says "Honestly I don't really like the workflow of having all my busses mixed in with my track strips (that's just me). Too messy and confusing."
 

+1 to this.
 
I also think there is a definite advantage in thinking about busses and folders differently: folders are for organisational purposes and should be focused on and optimised for that; busses are for mixing and should be focused on and optimised for that.  Mixing their functions affects their usability and clarity.