If sports are your thing, you could do worse than to picnic at Banff's Recreation Grounds. The Recreation Grounds are where the quaint mountain town of Banff hides it's sports fields, off leash dog park, skate park, and other activities for the athletically minded.
The picnic facilities are surprisingly good here, with a selection of picnic tables, benches, multiple picnic shelters and some rare and hard to find fire pits in a national park. You'll also find washrooms, water, and firewood on site. Not bad for an area devoted to sports.