Sweet, another Sig owner! Man their guns are like crack to me. I would highly recommend checking out Nill's grips: http://www.nill-griffe.com/ They are some of the nicest around for Sigs from what I've seen.
I would avoid the P229 Elite factory wood grips, just fyi. After having held a P229 Elite, I was in complete and utter shock. The grips made the gun seriously like nearly 2" wide across the back half! The thing looked like a steamroller or something! Definitely excessive on the width with those grips.
Yes, I tried out the grips on a new P229 Elite and they were way too fat for me. The P229 isn't the thinest grip even with the factory plastic standards. I went with the short trigger and that really helped with the trigger finger reach.
I've heard the Nill's are some of the thinest around and will look into them.
Not sure about commercial grip makers but make sure that the wood blanks were stabilized (soaked in an epoxy resin under high vacum till all the voids and cell structures are filled with the resin. It increases the weight but the wood will never crack, dry out or shrink). It also allows the grips to be made thinner without sacrificing strength. The same process is used for custom knife handles and scales. Do a search on ebay for "burl scales" or "burl grip". Lots of nice 1911 grips there. SIG grips are a lot tougher to make