I'm finally getting around to learning mastering techniques. I recently did a synthesizer arrangement of The Planets. Now I want to try out different plugins for compression, limiting, and EQ and compare results. I'm currently using the IK Multimedia White 2A for limiting, and the British NEQ-1972 for EQ. 

What do people here think of FabFilter Saturn? I understand you can define various frequency bands and apply different effects to different bands. I'm wondering if I'll get good results compressing the bass more than the mids and highs.

Thanks!

It's very cool, amazingly versatile and worth demoing. But it is essentially a distortion plugin.

The IK White emulates an optical (LA2A) compressor, so it's for leveling rather than limiting. Tonebooster's Barricade is a proper limiter and cheap, or you can spend $200 and get Ozone. 

Mike,
 
I recently listened to some of your Planets transcription and was very impressed.  I also watched a video interview you did.  What I don't recall is whether you mentioned what DAW you were using.  Anyway, two observations.
 
First, if you're not an experienced practitioner of techniques like compression and EQ, then almost any higher-end DAW will have more than adequate plug-ins with which to learn effective use.  Certainly Sonar does.  So there's really no need to spend anymore money near term on mixing and mastering technology, IMO.
 
But Saturn ... ah, Saturn!  It's brilliant and I'd hazard a guess that it's the single most useful tool you could get your hands on for polishing and enhancing the work you've done so far.  Not that you need to redo all your Planets tracks to make massive changes, but you might find some subtile seasoning that would improve what's aready quite good.  So, yes, check it out, but not for the reasons you stated in the OP.
 
Saturn is a little pricey, but FabFilter is currently having a bundle sale from which you could pick up Saturn, plus FF's filter and delay plug-ins, Volcano and Timeless, for a modest per-effect price.  Both are well-worth having, but neither are as indespensible as I suspect you'll find Saturn to be.