What part of the rockies? BC is a big place. I'm assuming your going near Vancouver/Fernie area and avoiding the Jasper (AB), Smithers, Valemount/McBride, North part of the province area.
Most times are great to go for shooting the landscapes. June, July, August are going to be for maximizing sun and minimizing bad weather (but maximizing tourists). If your near the coast, October is when the rainy season starts, and some mountains will get snow. Mid to late October, your looking at most mountains having at least a dusting on their higher sections, while lower down it'll be chilly, but shouldn't have that much snow that sticks.
How long are you looking to spend? Canada is a really big place, I could happily (and I have) spent months in the National/Provincial parks around Fernie, Blairmore/Coleman, Canmore, Banff, Lake Louis, Jasper, Prince George area. If your looking to maximize views of mountains, look around Banff and Jasper. If your going for animals, look into Jasper National Parking during the early/mid fall, and you should see a fair number of animals.
If you want more info, just shoot me a PM.