I see presonus has it as well. Im running to.

You must not have read post 19. 

Not game changing but definitely a nice option to have. I constantly use buses and having one channel assigned to two different groups would be very useful

John
The interesting thing that was posted above about sends being not well controlled with buses v VCA is a little bit interesting but may not be much of a problem in reality.  Buses can be a source for a send too. That seems to me to handle the issue described above well enough.
 
In the end it wouldn't hurt Sonar to have VCA faders as an option. I just think their usage as being a requirement is  a little exaggerated. Nice to have but not a requirement.   

The issue with Send relative volumes is a frequent issue. 
I do individual drum processing as mentioned by Dizzi45Z in #17.  Usually, things are fine...until I want to make a significant change in the drum presence.  NOT the end of the world but it's a hassle.  A VCA fader would definitely help out.
 
I also recently had this balance issue in a string quartet arrangement I made for a remix of Little Empire's song "Bullet" : https://soundcloud.com/user-581876462/bullet-reimagined-i
The string arrangement is a critical part of this slower bluesy-ballad version.  (The original is a faster alt-pop-rock tune that can hear if you search on Amazon / iTunes.)
I used two sets of strings quartets as the OP mentioned.  Rebalancing the individual tracks was not much fun and a VCA fader would've been nice.
 
There is another use case:  heavily layered rock guitars.  I love Brian May's use of these in many Queen mega-hits and love coming up with my own homages to his style.  VCA faders would really help out there as well since he's essentially making jazz-trios or orchestral arrangements using many guitar layers.
 
Will I run from Sonar cuz I don't have VCA faders? Not likely. 
But, as you alluded, it would be a nice added feature that most other world-class DAWs deliver.
 
(BTW - having the same features as other DAWs helps me move / migrate mixes between DAWs that other folks use.  Also, when I see a technique, I can easily adopt (steal?! LOL) them and use them in Sonar.)

Dizzi45Z
For example. Let's say you have all your drum tracks routed to your drum bus. Your snare track probably has a different amount of reverb on it then your Kick and etc., thus you have the reverb sends on the individual tracks, not on the bus. Well, if you turn your bus all the way down, notice you still hear all the reverb from the auxillary sends of the individual drum tracks. So, if you turn up the volume on the drum bus, the drums will have less reverb. If you turn the volume down on the drum bus, it will have more reverb. This is usually the exact opposite of what you really want.

Couldn't you group the reverb bus output with the drum bus output so the amount of reverb tracks the drum bus level? 

Anderton

Dizzi45Z
For example. Let's say you have all your drum tracks routed to your drum bus. Your snare track probably has a different amount of reverb on it then your Kick and etc., thus you have the reverb sends on the individual tracks, not on the bus. Well, if you turn your bus all the way down, notice you still hear all the reverb from the auxillary sends of the individual drum tracks. So, if you turn up the volume on the drum bus, the drums will have less reverb. If you turn the volume down on the drum bus, it will have more reverb. This is usually the exact opposite of what you really want.

Couldn't you group the reverb bus output with the drum bus output so the amount of reverb tracks the drum bus level? 

Anderton

Dizzi45Z
For example. Let's say you have all your drum tracks routed to your drum bus. Your snare track probably has a different amount of reverb on it then your Kick and etc., thus you have the reverb sends on the individual tracks, not on the bus. Well, if you turn your bus all the way down, notice you still hear all the reverb from the auxillary sends of the individual drum tracks. So, if you turn up the volume on the drum bus, the drums will have less reverb. If you turn the volume down on the drum bus, it will have more reverb. This is usually the exact opposite of what you really want.

Couldn't you group the reverb bus output with the drum bus output so the amount of reverb tracks the drum bus level? 

 this is a Feature Request for VCAs! not a "how do i..." :-)

John
You must not have read post 19. 

maybe he did read post #19, but didn't agree? just because you don't find a use for them doesn't mean anyone else doesn't!
and where do you get the time to use 3 (or more?) different DAWs to any seriously deep level, and still post so much on the forums??

If nothing else, VCA channels should be added to Sonar simply to keep up with the other daws.
Competition is everything. I can see someone choosing another daw, because of that one feature, because it provides them with a familiar workflow.
Perhaps, when someone sees it available in another daw, they think that Sonar is lacking in features. This is what marketing guys thrive on.
 
Pro Tools native got it last year. It used to be only available on the HD systems.
Cubase has it.
Studio One Pro has it.
 
 
 
 

mikedocy
If nothing else, VCA channels should be added to Sonar simply to keep up with the other daws.
Competition is everything. I can see someone choosing another daw, because of that one feature, because it provides them with a familiar workflow.
Perhaps, when someone sees it available in another daw, they think that Sonar is lacking in features. This is what marketing guys thrive on.
 
Pro Tools native got it last year. It used to be only available on the HD systems.
Cubase has it.
Studio One Pro has it.
 

To add to that: Logic has it, and Reaper 5 too. Samplitude ProX2 too, but a lite version not allowing nesting.
 
From time to time the years I spent at Cockos forum there was a riot from just a handful of people over VCA's.
And there are a lot of professionals that use Reaper - and somebody made a JS script and a description how to make it happend in Reaper 4.x, but rather cumbersome.
 
Still they introduced VCA's in Reaper 5 - probably as a you say to keep up with other daws.
 
Sonar has pretty advanced control groupings with the non-linear options - so I think it's not such big deal to fix the sends adjustments as VCA do. Probably more work doing the nested thingy and the flexibility that comes with that.
 
If Gibson Pro Audio are serious about that name - I think VCA's are missing to be competing with the rest.
Since release of X3 I felt a determination from Cakewalk that I never saw before - and last year even raised that further.
 
Check out youtube and search to find tuts on VCA. Some are not that good, since they give the impression same approach can be done with control grouping and are just confusing in that sense. ProTools Basic VCA's part 2 is good in giving a glimpse of grouping not only faders but any control and then a VCA master controlling that. If then automating VCA master you start getting the picture and how flexibile it is. Finally you can burn automation from VCA master into all the tracks it controls if you want. The amount of time saved in doing that is substantial - since there can be hundreds of tracks with their sends that are adjusted just right for you in a flash.
 
Sonar has this relative trim movement(activate on control bar) of automation which is difficult to see how much you affected. Both ProTools and Cubase has a second automation curve for relative movement that can be finally burned into automation. And they have this for VCA's as well.

MatsonMusicBox
It's actually really flexible as you can something belong to multiple groups at the same time - I think you can get "most" of the way there with groups and busses in SONAR. VCA technology is the standard grouping methodology in high end desks.

Let's see taking the OP's original requirements - he could:

Put all of library 1 on buss A
Put all of library 2 on buss B
Group Violins together
Group Violas together
Group Cellos together
Groups Basses together

I actually think that covers it per his original request.

If you have any sends on those groups - you will have to see to that all the returns of those send receiving tracks are routed to the same bus as well.
 
Look at VCA fader as a birds eye perspective fader, just altering automation levels on all assigned tracks for both volume and sends(and other controls too if you want).
 
You can go crazy on busses and routing doing just about the same thing - or keep routing more flat to one buss level only and use VCA faders to control it all.
 
And please note, just manually moving a fader on a track with a send, will not adjust the send to actually give you the same sound but lower. The send needs adjusting separately to keep the same sound. VCA do that properly for you - so the relative movement(called offset mode in Sonar) keep the right amount of send not to make final result more or less wet.
 
One not bad tut on VCA for PT:
https://www.youtube.com/watch?v=hgHNubKccrc
 
Especially looking at that tut make you realize how different one scene on a video change which music goes with it.
Depending on genre it may be different how eseential or helpful VCA's are - but really nice to know they are there as the project grows - like post production will maybe more than pop songs.