big white is kinda out of the way and made me realize how little you planned this.
Kelowna is the town by bigwhite and there's "one" boardshop, and premium label outlet. Those are generally the two to go to, in terms of outerwear. There's freshair experience concept as well, which sells park skis ect.
Comor on West 4th and Burrard (Pacific Boarder and a couple other shops are around there as well) or North Shore Ski and Board on Lonsdale in North Van. If you're headed to Banff from Bigwhite/Kelowna, I'd stop in at Attridge Ski and Board in Vernon.