Butchart Gardens is an excellent choice, with the interest.
With whale watching, you do need to consider, that the ship contracted tours are shorter than the regular length. Which means- the orcas have to be within closer range, and on average, have less sightings, figure 65-75% of the trips. This is average, and no way to predict.
When I go to Victoria, I always book at least 2 orca trips to hedge my bets. The operator will also KNOW before you leave what you will see, but don't count on them telling you, it's too late to cancel anyway. But I find out, for added bookings and don't hesistate for sucessive trips, especially when the 3 pods come together.
Read up on the southern Resident orca pods, JKL, for better understanding.