I did that once at YYC. I used to work there so I knew there was this large room in a restaurant overlooking the tarmac that they rarely used (sort of like an overflow room). I bought a sandwich and worked for about 3 hours or so. I stayed so long the waitress forgot I was there. It was a good change of scenery.
That spot was being renovated the last time I was at the airport so unless you want to hangout at Montana's there wouldn't be many other spots around to set up a laptop anymore.