I'm going to experiment with R-Mix to give a particular track a widened mix. Take one synth track. Add two sends to two busses. One bus panned hard left the other hard right. The main synth track panned to centre.
Add R-Mix to the effects bin of both busses.
In the bus panned hard left, in R-Mix position the rectangle such that it only includes the left hand side of the spectrum. And you could probably size the rectangle to eliminate some rogue stuff that is already to the far left, unless it brings something to the party.
Repeat the process for the bus panned hard right.
You could then add some subtle reverb or chorus effects to the busses and something different to the track.
Probably a load of rubbish all that, but I might give it a go later tonight and see what happens. The Sonar routing options might scupper me plans... At the end of the day, I'm trying to think of ways I can use R-Mix other than for "cleaning" up audio.