There are many plugins bundled in Sonar that I have little or no experience using, and multiband compression is a tool I never used before today.
 
I've been getting a mix close to the reference that I chose, but not close enough.  And when I'd apply the Ozone Maximizer to a decent mix version, I'd end up with tons of low end, tracks out of balance, worse, not better.  I usually EQ individual tracks for annoying/pleasing frequencies, but then I'll grab an Ozone EQ Pre-set and make adjustments to the exported mix there.
 
Now, I had a compressor on the Mix Bus, and it worked well gluing the tracks together, but I still couldn't get the balance I was hearing in the reference song.  First I grabbed the LP-64 Multiband, but I don't know that plugin either and the interface is a bit daunting to me - I feel the same about the LP-64 EQ for some reason, more homework.  
 
I put the Sonitus on the Mix Bus, selected a mild mastering preset, set the band widths by ear, barely touched those bands with compression if at all, and then adjusted the gain of each band.  It was the 1-2 db of +/- gain on the bands that really had an impact and fixed the mix.
 
Thank you Sonar/Sonitus.

I use the Sonitus multiband on virtually every project.  It is great as a mastering multi-band compressor.  I seem to be able to dial up a cohesive mix more easily than with any other tool.  I also love the Sonitus gate, as it is so tweakable.  And I put the Sonitus reverb on everything!
 
CW really struck gold when they picked up the Sonitus suite.  The Sonitus FX are without a doubt my most used, go-to FX.

BRuys
I seem to be able to dial up a cohesive mix more easily than with any other tool.  I also love the Sonitus gate, as it is so tweakable.  And I put the Sonitus reverb on everything!

I was amazed.  'What sorcery is this?'  I use the gate too, and sometimes the reverb.  Of course, now I'm looking at the LP-64 and it makes more sense:)

I have found the Multiband EQ useful in my symphonic mixes. It takes out a lot of the muddiness which is always a problem in orchestral music. I use the Subtle Analog Warmth preset. It does work like magic!

I love the Sonitus effects, and I know it is partially due to using them pretty much exclusively for the last 10+ years, I know them very well.
 
Whenever I thought about switching DAWs, a very big reason not to was the Sonitus suite. (I know it is now available as VST/32, but at the time, they weren't)
 
 

I've always liked the Sonitus compressor and reverb. Probably used hundreds of instances of those plugs over the years. But now that I'm on Sonar 2015 I'm going to try Breverb and the channel compressors. 

There is an (I think) excellent discussion of compression in general and multiband compression in particular (comparing the Sonitus and LP64) in the Sonar X2 Advanced Workshop Producer Effects tutorial, starting at 40:45 and 1:03:01 respectively.  I think this maybe available in later bundles, too?  I still go this to this occasionally when using a corner of Sonar I'm not so familiar with.  Excellent, as indeed are the Groove3 vids, Scott's Power books, and, of course, the stuff from the peerless Craig Anderton.  How these guys get their heads round all this stuff and still have time to make any music is way beyond me.  V. grateful here, anyway!

sonitus eq & verb & multiband here i love them