The other option is a remote desktop such as Splashtop. It mirrors your PC screen on the iPad, so you can have all of Sonar on the ipad screen, or you can pinch-zoom to focus on a small section. There's a keyboard that pops up if needed, cursor keys that can persist on the screen, and left and right clicks are done using short or long touches. You can even swap between monitors if you have two on your PC.
It's set up for working on a LAN, but if you have a gmail account, it can also work at distance over the internet. I've used it for work while traveling, and it is remarkably effective.
Cheers, Peter.