Lynn Canyon and Grouse Mountain will be much tougher to cover properly than Granville Island and Stanley Park!

It really depends on what you and the family like and want to do. For example, they may have much more fun at the open air pool next to Stanley Park than the Park itself! Granville Island has a nice kids market, but overall it is very crowded. Neither of them will take much time, though. The kids might also like playing near the lake in Stanley Park, but the parking can be very tough.

Lynn Canyon and Grouse both require much more walking than the other 2 - even if you take the Gondola up Grouse. Up top it is pretty much 'just' walking around, though they will almost certainly see bears under the gondola and lumberjacks at the top .

Some more details on what you would like to see/do and where you are staying would help others reply better than I can.

Dr. PITUK