mdages
A nice idea would be some voice controlled commands for Sonar, maybe a little bit Siri to Sonar? 
VoiceAttack will give you all that and more for very little outlay, but it's still a bit gimmicky at the end of the day. I think the point here is that 'options' should be the key - everyone works in a different way and if Sonar provides flexibility to accommodate that then it should.
On my setup I have 3 screens, an X-Touch controller, and an additional wireless mini-keyboard that sits on my main midi controller keyboard to save me twisting at 90 degrees to change patches or transport. I don't really need an app in addition, but it could be useful for some. Spectrasonics have a great app that sits alongside Omnisphere to give control over the multi's as well as the Orb.
I'd like to see the obvious transport controls in a Sonar app, but also something more innovative such as sliders for eq, panning, ACT for synth filters etc. That would be great for automation writing.
I also predict that before the year is out people are going to be asking for Rift and Vive support. Anyone fancy something like 'Fract OSC' as a genuine DAW?