I would not take the large touch screen route if you're into long mixing sessions and want to work "console style" ... but that's just my personal opinion ...
You could possibly get a VS-700C (the console only) reasonably cheap - there are many floating around. it's still a great controller for sonar ... I wouldn't bother with the VS-700R, there is better stuff out there (the VS-70R is too noisy and and it got Roland drivers which are not as stable as probably RME or likewise) ...
As regards new control surfaces ... well, there aren't many choices ... most are limited, especially when working with Sonar as you only have the Mackie protocoll that hasn't been updated in a long time ...
But if you are in an experimental mood you might build your own custom solution. Look for posts by azslow3 or PM him - he is working on a new generic control surface plug in ...