Consider a day trip (long) to Seattle to go to the Experience Music Project. It's that good.
Not enough time though - what time of year will you be there?
An ice hockey game could be a good option, and the chinatown a bit out from the CBD is well worth a visit.
Tim Hortons...
Granville island is a nice place to wander around, a bit touristy, but good history.
Stanley Park is a grand old park, hire a bike and go for a ride if the weather is ok (good luck!)
The gas town district is also pretty touristy, but interesting architecture and a steam powered clock that's a good photo op.
We also did the Rocky Mountaineer over to Lake Louise. Not cheap, but absolutely stunning! Go for the middle class (silver leaf) service - bigger windows, better food (not quite as fancy as gold) but we had a lounge car that more than made up for space, considering the wife, 18 month old and I were almost the only people using it. A whole rail car to ourselves!!!
If you do go on the train and spend the nigh in Kamloops, go to The Noble Pig for a beer. It's in the desert, in Canada!
Then we spent a night in Lake Louise on the lake - book early for a much better price. Banff, well, skiing isn't my thing and it was June, but it was a pretty place with nice walks.