There's not much to do in Whistler right now... BUT if you are driving here are some MUST do things:
In Vancouver:
Eat japanese food (try Toshi's, Tojos, or Shiro... check them out at dinehere.ca)
Go up Grouse Mountain and see the beautiful city, watch the movies, and enjoy the mountain life! (Dont forget to take pictures)
Go for a walk along the sea wall in Stanley Park.
Go to BC's biggest mall: Metropolis at Metrotown which is in Burnaby. (totally worth seeing)
Grandville Island is a good place to see lots of different cultures and many unique shops. They also have a really good marketplace:)
In Seattle:
Pike place market has lots of cool stuff (even the very first starbucks!)
Check out the harbour and take a tour on the boat ( dinner cruises are awesome!)
Eat at the cheesecake factory! It's really crowded but pretty good and it's just a cool place... they're also open late.
Space Needle in downtown Seattle is really fun because you get to see Seattle from up high.
Hope you have fun in Vancouver! Too bad you are going to miss out on the olympic action though...