When you arrive at Vancouver, Whistler is just 2 hour drive, you can rent a car, although I don't recommend it that much as in whistler everything is walking by, so your best bet it to hire in advance a shuttle. Or What I did last time was to rent a car in Avis and drop it in whistler it was a bit cheaper than the shuttle
I recommend to stay at Westin Hotel or hyatt they have great location right next to the gondola. The four seasons and Fairmont hotels are on Blackcomb mountain, which is only 5 min walk, I stayed at the four seasons over the summer and really liked it.
Ride the gondola up, there are a lot of trails you can hike, i was travelong with my kids, and they really loved it, they were searching for wildlife and such. Also you can ride the peak to peak gondola and change mountains.
It took us almost all of our day.
Whistler is known for the bike trails either on top of the mountain or down, so rent a bike from either of the shops on the village, and start exploring
There are a lot of trails that will take you more than a day, so you can explore the next days. Also I recommend, the ziplines, river rafting. If you stay 3, 4 5 nights or more you will always find something to do. If you are travelling with kids on the bottom of blackcomb village there´s a lot of options for them where they will have a blast!