Grew up with time split between Vancouver and Europe, myself. Moved to Calgary six months ago. Don't regret it at all, really.
I'll preface this by stating that I don't have kids, myself; I don't really like them, and I don't intend to have any, so I can't provide much perspective on what it would be like for a family, beyond stating that the public schools here are quite good, as are the charter and private ones, and there's lots of park space and youth organizations on top of that.
Speaking from my background, Calgary still has more opportunity than where I came from in Vancouver; Vancouver looks great on a postcard, but the cost of living (not just housing, but everything) is atrocious, the wages poor compared to the national average, and it has some serious growth-related issues, not to mention a poor job market. By comparison, Calgary is far cheaper for practically everything of substantial cost (housing, taxes, etc.), there are still more job opportunities here than in Van, and while not the mild-climate of the West Coast, it's quite reasonable here by Canadian standards, and the scenery is pretty solid - lots of big hills, the rockies are less than an hour away and clearly visible as long as it's not foggy/super-cloudy, so I call that pretty.
Why would I leave? I intend to retire in Europe, but that's more than thirty years away, most likely. I'd never go back to Vancouver - it simply isn't worth the price tag. Similarly, I could not imagine moving to any of the other major Canadian cities - Edmonton is too flat and too remote, ditto for the prairie capitals. Toronto is simply too damn big, and Montreal is appealing, but the Quebec economy is poor.
Draw-backs? Well, the cold winters are far rougher than most of Europe. The really unpredictable summer/spring/fall weather is annoying; the second day after we moved here was a freak hailstorm - ice chunks about half the size of golfballs turned my wife's car into a dent-fest. I do find some - emphasis on some - Albertans to be incredibly Right-wing, which for a European/Vancouverite is a bit off-putting, but in my view, that 'faction' is a shrinking group; even if people were super-pissed at the PC's, there's no way the NDP would have been elected, let alone to a majority, if many people were not now looking more 'Left' than they used to.
This is a good place. I think, size-wise, it provides all the advantages of a well-developed city. Nature/outdoors-wise, it's surrounded by nice lakes, the river is great, the parks are huge, and the Rockies are at the doorstep. The drawbacks, in my mind, are either becoming less of an issue (politics) or are temporary (oil won't tank forever).
Your mileage may vary, but this was the best fit for me. I'm still working to find full-time employ, but the opportunities are far greater, people are very nice, and I'm not too far from family/friends back in Van.