Walk the bike paths on either side of False Creek using the little ferry boats to go back and forth; with a lunch stop at Granville Island.
ferries
You can walk down the hill from either the Worldmark or VI timeshares to False Creek. Though July is prime time and it will be difficult to get into those spots for a few nights.
South of town, near the town of Delta is the George Reifel Wildlife refuge. Nice trails and lots and lots of birds including a family of Sandhill Cranes that started from a single male who decided that flying to New Mexico for the winter was too darn hard.
Reifel bird refuge
Walk the outer edge of Stanley Park or rent a bike. The walk along the water is my favorite. The park is huge and there are a lot of different options to help your kids expend some energy.
Victoria is great and one of my favorite cities, but with only 4 days, I'd skip it for this trip. Or choose Victoria over Vancouver. Splitting the time between the 2 means a lot of time getting from one to the other. The ferry ride from Tswassen is beautiful, but expensive. You could take one of the float planes from Vanc to Victoria's Inner Harbour. There's a very good museum next to the Parliament buildings right on the Harbour plus more walks and more of those ferries to get around.