Trying to get some more answers...
Flying YXY - YYC and YYC - YUL next month.
Arriving at YYC around 4 PM, flying out at 1:15 AM. Not sure how to kill the time (9+ hours!)

Domestic only the Chinook lounge offers walk-up (paid) access. Even at a discounted fee (US$27), it's only good for 3 hours and will close around 10:30 PM. Reviews aren't exactly positive and no real food is offered.

I was thinking about getting us (my better half is travelling with me) a room at the Marriott In-Terminal hotel for leaving our hand luggage, grabbing some complimentary food in the concierge lounge, access to a shower, a bed, could even do a dip in the pool. Not too bad for CA$ 180 (+$22 taxes), which I can deduct in my taxes anyways and gets me points. That's roughly the same price as paying 2x 3h per person at full rate in the Chinook lounge.

I'm wondering if it's worth it going somewhere else. Taxi gets us downtown fast, but will probably be pricey. The bus will take at least an hour in each direction, which leaves 4-5 hours downtown.

What's the ultimate survival guide to long YYC airport connections?

P.S. This is actually on our return trip home. When we're flying out, we also have an over-night lay-over and specifically took an early flight in, so we have time to visit downtown a bit.