I have found the Evanston Northwestern Medical Group to be extremely convenient. The last two times I woke up with a serious ailment, I was able to get an appointment that day! It was a relief to be able to see a doctor and get relief from my worries. I also trust my doctor because she was confident enough to refer me to a specialist rather than ignoring my symptoms.
The offices are right by the EL and Metra stop in Evanston, so it's pretty convenient. The facilities seem kind of old, but the staff carry about in a professional manner.