I don't think there are really any "must do's" in Vancouver.
You can probably find a couple of threads on this topic but the big hitters are stuff like:
Granville Island
Stanley Park/Seawall/English Bay
Canada Place/Convention Centre/Jack Poole Plaza
Grouse Mountain (admission fee with activities) sounding not so festive with the lack of snow.
Capilano Suspension Bridge (admission fee with other activities). Lynn Canyon Suspension Bridge is free.
Dineout Vancouver and the Push Festival are currently going on.