I would disagree with the notion that "just doing OK" will kill your chances. As far as Georgetown went, you really had to slack off to do badly (they really helped the students in terms of finding ways to "massage" the grading curves for our benefit). As long as you had above a 3.0, you hadn't put that nail in the coffin. I had an undergrad SGPA of ~2.8, CGPA of ~3.0, and I only had a 3.2 in the program (halfway through the year, my mother was almost killed in an accident and that had me a "little" distracted). So far, I'm in at an osteopathic school, and I have three interviews coming up at allopathic schools. Of course, it certainly helps if you do outstandingly well in the program, but as long as you at least "keep up" and don't flunk out, you'll be fine.
And doing well isn't that hard if you're focused -- I had one friend whose undergrad GPA was supposedly similar to mine, and she finished with almost a 4.0 and is now a first year at G'town.