My experiences are the exact opposite when it comes to liquor distribution. In Calgary, stores have good specials on beer, wine and hard liquor all the time if you shop around. I can also get fantastic service at several specialized wine shops. I spend about twelve weeks a year in the B.C. Interior and the liquor store hours are terrible (still closed Sundays and holidays, only open until 6 pm every night except Friday until 9 pm. I find the prices in B.C. very similar to Calgary's regular prices, but then B.C. adds an additional 7% tax at checkout.
I don't know anyone who goes to B.C. without buying their booze in Calgary first. If you are paying less in B.C. you're probably not shopping around for the best deals. We figured out that we saved over $100 by buying $500 worth of booze in Calgary before heading out last summer. That wasn't even including the 7% PST in B.C.