Purchased the Sasquatch combo, which is really the only thing to do! Start off with the sasquatch line which is 2 km long and can reach speeds of well in excess of 100 km/hr. This is the longest zipline in North America. Can race alongisde a friend as there is dual lines.
Once that's over, the remaining 5 zips are relatively tame in comparison but enable you to experience other things - going upside down, trying to steer, or cannonball (speed up).
We hired a go pro to document the experience, as no cameras or phones or loose objects allowed. In zipped pockets would be fine, but at your risk. Go pro needs to be picked up from the base of Whistler Mountain, but the tour starts at the base of Blackcomb Mountain (10 min walk). Lockers can be hired from the base of both for about $10/day.
Bathrooms only at the base, so be prepared. No food or drink able to be purchased once on the tour, but they give you a small bar and drink while on the tour.
Our guides Bjorn and Kiah made us feel welcome, were friendly and chatty, and never once did I feel unsafe.
Bonus we managed to find a black bear crossing a track ahead of us which was pretty special to see!
It's expensive, but worth doing for the experience.