Vancouver Island is easy to get to.

You've got 2 choices.........take the BC Ferry system...........it's the longest trip at 90 minutes on the water to Victoria, but it is also very scenic. A car costs $57 plus $17.50 per adult in the vehicle. Problem is, you've got to get to the ferry port first, so you'll need a car or taxi as it is located far away past the airport, you need to wait at the dock, etc, and there is a very limited schedule. The 90 minutes on the water becomes 3 hours more or less. If you can't handle boats on the open water though, you'll need to fly.

https://www.bcferries.com/

You can fly on a seaplane, just walk from your hotel to the terminal on the water (15 minutes), and get on board. $76 CAD to Nanaimo one way, or $156 CAD to Victoria one way per person. The seaplane lands right in the center of the port in either city, and you are in the middle of downtown and can walk everywhere. No need for taxis, a car or parking, etc. If it is just the two if you that is what I would do. My wife and I do this all the time.

https://www.harbourair.com/

Otherwise, its back to YVR for an Air Canada or Westjet flight.

Day trips ? The island obviously, Victoria is gorgeous, just walking thru downtown Vancouver which can take a day easily (start on Robson and go down, Denman, Davies, Granville, it's a big 40 block square walk), as you'll get side tracked by the sights. The marine aquarium in Stanley Park is really cool too.