Just because you want to go for a picnic doesn't mean you have to leave your dog at home. Sue Higgins Park is Calgary's largest off leash dog park covering 62 hectares, but it also has a couple of picnic tables in Nora Tuckey's Grove which are independently fenced off in the south west area of the park.
The rest of the park is a dog (and dog owners) paradise, it's fully fenced, has a mix of grassland and wooded areas, and a bunch of access points to the Bow river for the dogs who love to swim. Ample garbage cans are scattered across the park for your poop bags and there are benches for when the dogs inevitably tire out their owners.
The parking lot is a bit small, but you can also access the park via a pedestrian bridge over the river to the east where there is a lot more parking.