Another option if you are just keen to get your kids hanging off some real rock instead of plastic is to take them bouldering. Enormously simplifies the logistics, arguably safer, and much easier if you have more than one munchkin to try to keep entertained. I really don't like bouldering much myself, but when the kids were little, we did a lot more of that than roping up just because it was so much easier.
SFU has a couple of fun rocks to hang off of (very easy up by Horizons, or a bit more interesting in the woods near Gaglardi/Ring Road). Murrin, Lighthouse both have a bunch of great spots where you can work on long traversing problems. Never bouldered at Chief but scrambled through there enough times to wonder if there is anywhere in there with safe landings? Green River Bastion boulders if you are up near Whistler/Pemby have hands-down some of the kid-friendliest bouldering I've found - large boulders, lots of V0 routes, and the ground couldn't get flatter or softer if they lined the whole forest with foam rubber.
