I have a close relative that was a premed Domer. I also know people who went premed at Northwestern (both the regular track and the accelerated 7yr program). My friends at both of these schools said the premed curriculums were pretty hardcore. I actually considered both of these schools coming out of high school, but I know more about Notre Dame's program.
If you'd like to have some more research experience (clinical or laboratory), I'd go with Northwestern--more resources are available. However, there are significant research opportunities at ND as well. I also think there are more extracurricular opportunities in Chicagoland, but I think you could access such opportunities without having to do postbac work at Northwestern.
As far as pure academics, I think either woud be a solid choice. One thing about Notre Dame though...My relative went through the BS Biology program for his premedical studies. A lot (maybe even most) of the premeds at Notre Dame go through the Pre-Professional Studies major. I'm pretty sure that's the name of it. Anyway, the pre-professional studies premed track tends to be a little less rigorous. My understanding is the GPA of these students is appreciably higher than the Biology BS program. When my relative was there, the Bio BS program had a higher MCAT average than the pre-professional studies majors, but I don't think there was a major difference. I *think* the pre-professional studies majors take some different prereq premed classes (I believe some are the same and some are different), but don't quote me on that. The courses taken by the Bio BS students may be more rigorous and may prep you better for the MCAT (again, I don't think it will make that much of a difference), but just know that you'll have your work cut out for you. I just thought I'd throw that out there in case you're considering which classes to take.
Personally, if I lived in South Bend, I wouldn't go out of my way to go to Evanston for postbac courses. You can get a strong education at the Dome. Also, have you spoken with Fr. Walter at Notre Dame? I think he's the Chair of the Pre-professional Dept. I would try to get some input from him and see what opportunities they can offer you at ND.
Good luck!
