Calgary Marriott Downtown.
I've stayed in most YYC properties as a local. Before a few months ago, I would have said the Eau Claire hands-down, and it still is a great hotel. However, my last stay was at the Residence Inn Calgary Downtown and I came away incredibly impressed. Don't get me wrong, the breakfast in the lounge at the Eau Claire is very good, but the breakfast offerings at the Residence Inn were unbelievable!! Huge assortment of hot and cold offerings, healthy choices - the breakfast food area must have been 1000-1500 ft2. Rooms themselves were spacious if not opulent and had full kitchens, and the fitness area at the hotel was on two levels and was quite extensive. It's also very reasonably priced. I'll definitely be back.
Cheers,
Singlepoint