Regional rail in Calgary feels more pro-suburb than pro-transit for me. A train to Cochrane sounds nice until you consider that it's 1/40 the size of our city. It's about the combined size of Taradale and Saddleridge. And unlike those places it has near 100% car ownership, and not everyone works in or has any reason to be in Calgary regularly. A single stop C-train extension in any direction would capture more riders.
A GO Train expansion outside the borders of Toronto, this isn't.
That said, I do think a train to Banff (or maybe Lake Louise) is a good idea, and a train to Edmonton is a good idea, and we might as well have a provision for stopping along the way in places like Canmore and Cochrane (and maybe even Bowness) to the west, and Airdrie and the airport to the north.