I am Canadian and have been thinking about decisions based on finances as well- it would be SIGNIFICANTLY cheaper to go to school at home than in the states- with the exchange rate there's probably a difference of at least 50,000$, if not more... I have pretty much come to the conclusion that it is worth paying the extra money if it is a school I really want- I do however have support that will make that possible for me, which I think is a factor to consider- if you don't have the funds to do it, I would choose the less expensive school. In the end it is at least two years of your life, and I think you should go where you think you will be happier and have the best experience- it sounds to me like if the two were the same price you would be choosing MGH. You will be able to make back the money and if you're good with your money pay back that extra 30,000$ without too much trouble. I would say follow your gut!
In saying that, I went to ASU for a semester a few years ago and did some of the speech classes there- they have an excellent program with a clinic in the same building as the classes, and the profs all seem great!....plus the sun is nice To my knowledge, you can probably request a hospital placement, but I don't think it is guaranteed- I know you do placements with each age group, but I'm not completely sure how locations are chosen.