This is the price we pay for living in the great white North.
Pretty much every car I've owned I've had to hammer the crap out of the rotors to get them to break loose.
On my last car, I used a little wheel bearing grease on the back of the rotor when installing new ones, and that made things a lot easier a few years later.
I also do the same (grease the inside) on my wheels/rims before installing them. They come off no problem when I need to swap them out or rotate them later on.
Getting back to your problem, one thing I did in the past was to re-install the wheel, but leave the lug nuts slightly loose.
Go for a gentle short ride in front of the house, and the weight of the car will break the rust bond on the rotor.
Sometimes just rocking the car back and forth with the lugs nuts on loose will break the bond. Not too loose though. You don't want to snap the studs.
Short story: A few years ago I was in Florida, and took my 10 year old Nissan Altima in to a local shop in Orlando for a new muffler.
The tech couldn't believe the condition of the underside of the car. He'd never seen anything like it. Canada eh.