Winging it in Jasper and Banff National Park

Something to be aware of is July 1st Canada Day long weekend in the Parks can be really really busy and you “may” have an issue finding a spot

Soup

In Jasper: Whistler, Wapiti, and Wabaso are prefered by many. More services. Whistler has full hookups, elec, or basic sites, showers, and nightly interpetive program. Wapiti's elec sites are in a converted parking lot. Wabaso is @ 20 miles south of Jasper townsite, on the old highway (93A). Backing onto the Athabasca river. (We'll be camping there when our childen are older). Less traffic, little out of the way. About 6 other rustic campgrounds in Jasper.
In Banff: Tunnel Mountain is the largest campground. Located on outskirts of town. Interpetive program, showers. Full hookups are ok. Power only site are basically nose to tail on one side of a paved roadway. Non serviced sites are very nice.
Two jack lake campground has spectacular views about 15 minutes out of town. I believe no sevices.
Johnston canyon and Lake Louise campgrounds popular as well
About 10 other rustic campgrounds in Banff park.
I, personally wouldn't camp near the icefields. It always seems to snow there on our annual Jasper holiday.
Waterton has 2 rustic cg (1st come, 1st serve) and a serviced one in town. They have a healthy bear population.
You might want to get a few reservations. If nothing else just to charge the batteries. Generator use is regulated.
Parks Canada reservation website has pics of each campsite (with reservable sites). Might give you an idea where you'd like to stay. (sorry, cant figure out how to post a link with my smartphone).
Hope this helps.

Moved to RVing in Canada

We have been twice to Glacier & Banff. Once to Jasper & Waterton. Never had a reservation, always found a place without much if any hassle.

We stayed by St. Mary's in Glacier. On the east side of Banff. At the town site in Waterton.

More on Q

As I mentioned, we have been able to visit Galacier twice, each time we have stayed in the park, which IMHO is always the best place to stay (in the parks). Both times we have stayed over by St. Mary and just off the Going to the Sun Hwy. But my son stayed down by Many Galaciers and then over on the westside as well. All are neat.

I believe I would try one of these on our next visit Many Glacier and Two Medicine and Sprague Creek. Also St. Mary is close to St. Mary Lake but not right on it as I remember. Map List of CGs

If you use US 89 in Montana to get to Glacier, they have a city park with camping at Choteau which is about 105 miles from the east entrance at St Mary's and 140 miles to West Glarier. We stayed at it, I believe, in '97, but do not remember a creek. We stayed in a city park, in the town, not sure if it is the same town. Looks about right on the map. There is overnighting at a rest area, closer to Glacier as well, near Dupuyer. Rest Area
City Park

They have a neat visitor center between Jasper and Baniff at a glacier, as I remember it, With a Tour on an Ice Bus like machine up on the glacier for a fee; but there was a short hike to the foot of the glacier near the hwy for free as well. The Bus was neat. Tours of Columbia Icefield Glacier, we have gotten to do it twice. Very neat. Take a jacket, it can be cold. First time was in '86 and we drove up from Baniff to see it and do the tour. Second time was in '97, we stopped going from Jasper to Baniff in MH.