You have made a great decision. A stay in Vancouver is something everyone should do before or after a cruise that starts or finishes in this great city.
For accommodations I recommend the Holiday Inn and Suites on Howe Street. VERY nice and reasonably priced with a great restaurant. Not too far from everything to do and see and close to Canada Place.
Places to visit are Grouse Mountain with it's fantastic view of Vancouver,(use a public bus to get there) Stanley Park, Gastown, Granville Island, (great food) City of Victoria on Vancouver Island with it's very British atmosphere and famous gardens. The list is endless. During the daylight hours, try one of the sightseeing trolley cars to get around the City of Vancouver. They stop at most points of interest and you can get on and off as you please. Have a great trip. Cruiseman