Tofino and Uculet are brilliant, we stayed just outside Tofino in a huge cabin by the beach. We went to Van Island as one of my best friends from school lives there.
Also think about some of the other gulf islands - we've been to Bowen and Galiano, both were lovely.
When we went to the Rockies we rented a huge RV and drove from Vancouver - really long drive!! But it was good to have the flexibility - we stayed in Jasper, and drove back over about 4 days via Banff, Yoho, and the Okanagan. My parents didn't rate the train very highly.
We've been as a family twice (Bil and family lived there for about 6 years), each time for 3 weeks.
First time we did Vancouver (it's worth giving the city itself at least a couple of days - try to have breakfast at Sophie's Cosmic Cafe in Kitsilano, and Granville Island is also good), Rockies trip, Bowen and Van Island to see my friend in Courtenay. Second time we did Tofino, Courtenay (it's just an ordinary wee town, nice but we only went because of friend), Galiano Island and Vancouver.
If you're going with children, there's some good stuff, especially the water parks and the aquarium in Stanley Park. Can highly recommend the Frommers book "Vancouver with Kids"
Have a great time, I'm quite 