I spent a good amount of time at the Calgary Airport earlier this month and it wasn't a bad place to spend a decent amount of time.
Airports aren't usually the most fun place to hang out for a long period amount of time, but I have no complaints about the Calgary airport. Every time I've been at YYC, I've taken a domestic flight, so getting through security has always been a breeze. There are barely any lines, and if there are lines, they move very quickly. There is plenty of signage, so it's pretty hard to get lost around here.
The domestic terminal itself has a few restaurants, Chilis and Molson Brewhouse to name a few, which are great to grab a bite and drink at to kill some time. There were also plenty of fast food restaurants and convenience stores around if you want something a bit quicker.
They also have great free wifi. It always frustrates me when airports have terrible wifi. But this is not the case for YYC. I was able to work for about 4 hours straight without the internet disconnecting once.
Thanks for being awesome YYC Airport, you give Canada a great first impression to first timers ;)