Thanks Jeff, I've been following that thread. I have tried to master in Sonar.  However, one of the main tasks in mastering is getting the compression, limiting and final levels all set, especially EBU levels, etc. I didn't find this as intuitive in Sonar as in Wavelab Elements 9. (I tried Ozone and prefered Wavelab Elements; didn't see the need for full Wavelab at the level I'm working at). I was also impressed by the Lurssen console.  It's a bit of a toy, but gets results quick, but I think I prefer more control over the payload. 

Sometimes I put a gentle reverb on a master track instead using a reverb bus. Makes the impression of a live recording in a room. There might be also some spring reverb on guitars as if I used the amp built-in reverb. But that is the mix decision, not mastering.

No meaning to hijack thread, but add meaningful content.
 
Do you always mix down to two tracks and then master, or just add another "Master" Bus once the Mix is completed.
This also assumes you master in Sonar.
I can only think of one reason for the "Master" bus idea.  It keeps all the files in one handy place.
 

I mix down to a 2-track master before importing that one track for mastering in a separate project.  Primarily because the LP EQ and Compressor take a lot of memory and it eases the process that way.