JBJ,
After I submitted my AMCAS in June, I thought about adding a couple more schools to my list. The reason I decided not to is that I think that when you make any sort of changes whatsoever to your app, as I'm sure you know, you must go through the whole certification, payments, etc as you did once before. This whole process would probably cost you at least a month (?) in time. If i were you, I would put alot of schools down and give up the 30 bucks for each. That way, even if you decide later on that you're not interested, at least you wont have to delay your processing by adding more. Just my opinion, hope it helps.