Lurie Comprehensive Cancer Center is one of the NCCN cancer centers (see http://www.nccn.org/members/network.asp).
Link to the Lurie home page: http://www.cancer.northwestern.edu/home/index.cfm
Link to cancer patient information: http://www.cancer.northwestern.edu/cancercare/index.cfm
The physicians relevant to GIST include:
Dr. Mark Agulnik (medical oncologist)
Dr. Jeffrey Wayne (surgical oncologist)
Dr. David Bentrem (medical oncologist)
Dr. Al Benson (medical oncologist)
Dr. Mary Mulchay (medical oncologist) not accepting new GIST patients
You can search on their site to find pages about these individual physicians.
I'm being treated at the Lurie Cancer center in Chicago and think they are FANTASTIC. My oncologist is Mark Agulnik. He's knowledgeable about GIST and was at Princess Margaret in Canada before coming to Northwestern (probably about 4 years ago). The center is VERY patient oriented and the support staff is great.