Have either you or your wife done any cold water diving before? Having a dry suit for BC is nice but not a must. It will keep you a lot more comfortable but I have seen people dive in 7mm wetsuits when it was -6 degree celcius so its really up to the individual. If you only have 2 days here in Vancouver, I would just concentrate on having a good time diving and not try to fit in a dry suit specialty course for your wife. To take the dry suit specialty, she would have to do some classroom and hit the pool first, that is going to be at least half a day already.
Best bet would be for her to take the course back home and both of you dive dry suit when you get here. Another thing to consider is that the 6th and the 7th is the weekend, there might be a lot of people at Whytecliff, parking can be difficult is you don't get there early (like 7-8am). Also most OW classes in Vancouver are held at Whytecliff, this doesn't help with the visibility. Personally I prefer Porteau cove, there are loads to do there and for different levels of fitness or skills. The bow of the Nakaya at hightide is easily 100 feet deep, but it is a long surface swim. There are also dives at Porteau that most divers don't know about, like under the pier and stuff.
Some other dive stores to consider are International Diving Centre, Rowand's Reef and BC dive adventure. I don't know their website addresses of the top of my head but you can google them.