I've also put in a feature request for this, but the idea is that the user can designate for example all tracks and data between marker 1 and marker 2 be designated as a single block called "Intro", marker 2 and marker 3 as a block called "vs 1", and on and on.  I would like to be able to set the marker to the barline and it automatically recognizes and captures pickup notes.  Then I would like an 'arrange' window or screen that these designated selections are a shown as blocks on a timeline that I can drag and drop to rearrange the order and try different versions of the song. 
I saw something like this in a competing product that I demoed a while back.  I don't want to learn a new product, I would just like to see this in Sonar :-)

Something like this would be really nice! :)
 
What would you want the blocks to do with clips that overlap these markers?
 
For example: If you've got a guitar recorded on the refrain and this riff ends with a chord that strikes at the first beat on the bar right after the refrain and sustains for a few secs... If you then take the refrain-block and copy and paste it later in the song, what should happen with the part of the clip that is outside of the block?
 
What I'd like to see is that the whole clip gets included, but also that it's gets truncated where the marker is located. You can then paste the block just before any other block without risking this clip to overlap a clip in the next block.
 
If there's nothing on this track in the next block, you can expand the clip to it's full length again, assuming that the block after is in the right key for the last chord to sound good.. :P

On the front side I would prefer that the blocks auto select any part of a clip that is less than a full measure at the beginning (to catch pick up notes) since I would want those most of the time when copying.  On the back side of the clip it could be trickier due to fading chords, etc.  I think your solution sounds like a good one.  I wonder if a selectable option could be available to have it truncate or autoselect any clip that continues for up to a measure after the block ends.
 
When I saw this feature in another DAW that I demoed I really thought it was a workflow enchancement.

+1
Personally would love to see the arranger as a header track which could always remain pinned (but scrollable) to the top of a view in track view, or be hidden like any other track when desired. (Feel free to straighten me out if this isnt what you had in mind.)

The basic idea is:
a) create an arranger track
b) set up any number of time ranges in a project. A range cover alls tracks as far as I remember and each get it's own nametag. Cubase implemented range markers in the same system as normal markers - with it's own style.
c) add named ranges as you want to a playlist on arranger track.
Each added range can be put anywhere in playlist, and each also be set to x repetitions.
 
Very useful to decide final flow of a project.
Easy to add extra parts at the end of the project, but insert it anywhere on arranger track.
Add a longer intro, extra breaks, extra chorus etc - or anything you come up with.
 
In Cubase you can save different arranger setups and also allow to either play project from arranger track, or generate completely new projects from any saved preset you made in arranger.
 
Even Cubase Elements have this feature.
But if Cake implement this I buy up to any version to get it.
Really neat...

I agree, Sonar really needs to be more user friendly when it comes to arranging. The current way of moving huge chunks of a project around by lassoing and dragging them, or by inserting or deleting time, are fraught with problems, finicky and inconvenient. Being able to define song parts or "scenes" and order them on an arranger track would be so useful and make mapping out songs so much easier.

I also think Sonar needs some kind of clip library feature like Pro Tools - a means of instant access to all clips in a project. It would be so much easier to be able to drag clips from a clip list into the project instead of scrolling back and forward along the clip window to drag-copy clips from A to B.

sharke
I also think Sonar needs some kind of clip library feature like Pro Tools - a means of instant access to all clips in a project. It would be so much easier to be able to drag clips from a clip list into the project instead of scrolling back and forward along the clip window to drag-copy clips from A to B.

I double that too - all daws I tested always hide away midi stuff.
They often have a manager/pool kind of thing for audio clips - but midi stuff is excluded - why?
Partly possibly because midi never become files on disk - so get them managed too, please.

sharke
...The current way of moving huge chunks of a project around by lassoing and dragging them, or by inserting or deleting time, are fraught with problems, finicky and inconvenient. Being able to define song parts or "scenes" and order them on an arranger track would be so useful and make mapping out songs so much easier...

 
Very true. I have a project that I put aside a while ago in which the verses, bridges, choruses, instrumental passages all sound good separately and the transitions between consecutive sections are ok too. However the whole thing played from start to finish somehow doesn't work. I tried changing the order of some of the sections but this took a lot of effort. Right now I don't have a clear idea of where I am going with this project and I would like to experiment with different alternative arrangements, but it's too much hassle so I've shelved it for now. With a suitable feature that would make re-sequencing easier I would continue.

my vote on this ... this sounds really cool because all existing options (clip grouping, matrix, ...) are too tedious and hurt the creative flow because you can just restructure on the fly ...

Yes please. This sounds like a great idea.