I couldn't think of a better place to turn then the users of Cakewalk Sonar Forum. I have my current setup listed below and wife was interested in buying me Christmas gift to "upgrade" studio. Figure I would get advice on what components anybody here might upgrade. My other option is to put the money towards my kids college fund ;)
 
ADK Pro Audio i7 machine
Sonar Producer X3c
RME Fireface 800
A-Designs Pacifica Mic Pre
 
Miktek C7 
Beyerdynamics M160
Shure SM7B
AKG C414
Shure SM81
 
Event Studio Precision Monitors
Beyerdynamics DT770 Headphones
Using all Monster Cables in studio.
 
No plugins besides what came with Sonar. Had almost bit bullet on UAD, or Waves or Softube line up. 
 
Think that's about it. Appreciate any advice or opinions really if anybody is that bored. 

Meant to say I guess for some background. Record mostly 1,2,3,4 piece acoustic stuff. upright bass, rockabilly, folk, jazz etc...

I think your hardware setup is good enough to last your for a while..
 
Since you mentioned there is no other plugins and you're doing mostly acoustic stuff ..how about some mixing/mastering plugs (Alloy, Ozone). Upgrade to Melodyne Editor perhaps ? Get a Groove3 yearly pass (it's running an offer this month) ?

If your wife really loves you she would buy you producer....

Buy me Producer? I use Sonar Producer X3c unless you are referring to something else? 
I had thought about the Melodyne comment. Wasn't sure if adding a new mic to arsenal or preamp was worth it either. Too much gear, too little time.

Maybe something from this page.

 "upgrade" studio
 
Ah sorry misunderstanding...
She does love you then :).

Nice set up - your wife will really have to drop some bucks to upgrade the hardware component.  I thought my wife was nice to let me buy a Portico II channel, but she didn't pay for it (and she still gets to sing through it).  But a good compressor is nice to have on your ins, just to pre-squeeze things a little.  It helps settle a track into a mix w/o stomping all over it.  Which to get?  Depends upon how much cash.  The FMR PBC is a good character comp - should work well w/ the A-Designs - and is about $400.  Some people like the Art channel, which is cheaper, but if I was in your shoes I'd go for the best quality she could afford.  Or have her get you a 500-series rack that you can fill in.
 
On the software side, the Softube Mix Bundle that came through Cakewalk was a really, really nice addition.  If it goes on sale again, have her jump on it.  It has a couple of pieces I use all the time - the verb (not so important now w/ Breverb), the FET is a step up from Cake's, and the focusing EQ is great.  Cakewalks Re3 leveling amp is another good buy.  UAD is still good, but that seems like a never-ending cycle.  The lastest software needs more CPU, so you upgrade the card but in a year you need another one.  Still, I know pros who have given up on their hardware and use the UAD.  And it is cheaper than good hardware.

You look pretty set on hardware for what you do. How is the physical space you are recording in? Sound treatment may help you more than any plugin or hardware based on what you already have.

Sound setup/absorption/traps etc is "ok". Could always use improvement and I do in little steps realizing it's never going to be top notch. 
Softube Bundle? I know it came with Nomad Factory Blue bundle but that's different correct.
 
But a good compressor is nice to have on your ins, just to pre-squeeze things a little.  
 
This was actually in the back of my head as my main option. The A-Designs Pacifica is awesome but either it's hot or the mics I am using (Mainly Miktek C7 and 414) are too hot, because I have to Pad it and have gain to almost nothing. I had thought about adding a comp before going into computer. 
 
I meant to add, budget would $1000, and I would spend a grand myself, so let's say $2k