As Mani says, there's great variety in Vancouver. I spent a week in the city centre last year, and was out most nights with the camera - it really is an excellent city for night architectural shots. Not sure what your preferred style is, but some highlights for me were the sunset over English Bay from our balcony (high on Robson St), the Olympic cauldron, sunset over the Coal Harbour from the Convention Centre, rock art on the beaches in Stanley Park, the 9 O'Clock Gun (firing), the view of the Coal Harbour/city centre at night from Stanley Park and the steam clock in Gastown.
While travelling light is nice, I certainly didn't - took a tripod, my favourite landscape/architecture lenses (Zeiss 21mm, Canon 24mm TS-E were my most used lenses), filters, cable release etc. I think I would have regretted not having my usual kit, so if photography is going to be a main goal, I usually put up with the weight and take everything I would expect to use. As an aside, I did a lot of walking around the city late at night on my own, with a lot of expensive gear, and didn't feel uncomfortable at all.
Whether you concentrate on photography or not, its a great city, so I'm sure you'll have a fantastic time. We spent the second week in Whistler rather than the Rockies (would have liked to go to the Rockies but needed to keep distances to a minimum), but the combination of the city for a week before the mountains is a good choice IMO. The first time I went to BC, we headed straight up to Whistler (Skiing), and I regretted not spending some time in the city.