You can take a bus to both places from Nanaimo but be aware that there is no guarantee that you will see a bear in either place or on the way to and from. There is probably a better chance to see bears on the cruise from the ship, imho.
We have a cabin in the mountains east of Vancouver (and Manning Park) and in the past 15 years have seen only two bears near the cabin and a handful on the drive from Vancouver. Many years ago bears used to wander through the campsites in Manning Park regularly - had one sniff my elbow from behind once - but authorities are quick to live trap them and move them farther away these days.
Now that fruit is ripening you have a good chance of seeing them in people's back yards in North Vancouver. You could take the gondola up Grouse Mountain (accessible via Vancouver city bus) in North Vancouver for incredible views of the city, sea and mountains with a chance of seeing wildlife but no guarantees there either.
We were in Tofino last summer and encountered a wolf on a trail - caused quite a stir when we reported it to the naturalist. A week later, near Tofino, a cougar attacked a small child while he was walking holding his mum's hand. Wildlife is unpredictable and encounters can be very dangerous - especially if it involves surprise or stalking! Aside from seeing bears, Campbell River and Tofino are spectacular places to visit.
Let's hope we see some on the shores of the hundreds of islands we will be floating past on the cruise or whales in the water.
Susan, Victoria, Vancouver Island, BC