Hey Mike,
I was also accepted to McGill and to Georgetown (with funding) for English. In addition, I went to McGill for undergraduate school and got a B.A. in English.
Chances are I'll be attending neither of these places but I think there are a few distinctive pros and cons to each that I'd be able to enumerate for you.
The pros of McGill are that it's cheap (Canadian universities are all heavily, heavily subsidized by the govt), and that, as opposed to U.S. M.A. programs, when you are accepted to a Canadian M.A. program it's pretty much implied, if you do reasonably well, that you will be approved to continue on as a sequential Ph.D. candidate. As I'm sure you know, this is NOT the case here in the U.S.
The cons of McGill are that it's freezing in the winter. Literally, absolutely, ridiculously, freezing cold. To the point where it's really not enjoyable to live there (I'm a New Yorker, so it's not like I've never been through a winter, but Montreal is another level). In addition, while the faculty is very good, it's not GREAT. I guess from what I've gleaned the faculties at G'Town and McGill are comparable, but you might find more folks at G'Town who have good ins with American Ph.D. programs. That brings me to my last point, while McGill is a highly, highly respected international institution, I think most of it's humanities Ph.D.'s have succes finding jobs at other Canadian universities. However, that's not necessarily a bad thing as IMO Canada is a wonderful place.
In terms of G'Town, I;m not nearly as knowledgeable (considering I've never gone there), but to me they seem pretty dedicated to getting their students into top notch American Ph.D. programs. In addition they have a wealth of extracurricular avenues of involvement (DC prison outreach program, DC schools project, etc etc.). It's also in D.C. so your opportunity to see various speakers and meet various figured will be much, much greater than it would be at McGill.
Anyway, thats really all I can think of for now, but if you have any further questions feel free to PM me.
Cheers,
BPR