Butchart Gardens is a must see!
If you are not going for snorkelling, I would advise you to only do a half day as you really don't need a full day (unless you want to lay on the beach all day). Viewing the sealife through the submarine was the main highlight for me - truly amazing!
I had a fantastic time on this tour.
There were 6 of us; all from different parts of the world and having just met, we all got on really well.
The tour guide, Fabian, was fantastic and was very knowledgeable about the places which he took us to.
I would certainly recommend this tour.