Gary's recommendation to see Banff, Jasper and the icefield parkway is a really good one.
Below I have listed where we stayed, what we paid per night and what was available, it is quite a list so I apologise if it's too long. Please bear in mind, this is what we did because we love scenery, eating and drinking, we're not into shopping or big cities.
As I said in an earlier post, we entered via Osoyoos, so I'll begin from there, and we started 1st of June, all prices are in Canadian dollars. FCFS (first come first serve site)
Route 3 from crossing towards Cranbrook to join 93/95 North.
We stayed at Boundary creek provincial park Greenwood, $18 per night, Flush toilets, FCFS would stay again.
Nelson, we stayed at Coolwaters RV park, $30/nt, flush toilets, shower, 30amp, water. Adequate site, rustic but functional, cash only. Nelson has good brew pubs, if you have time, do the loop to Kaslo, Nakusp and back through Winlaw.
Free ferry at Balfour across Kootenay lake on to 3A Creston and back on to 3. We stayed at Yahk provincial park, $18/nt, pit toilet. FCFS, Nice campground, would stay again.
Through Cranbrook on to 93/95 North. Wasa Lake provincial campground $30/nt FCFS, toilets, showers, water & dump.
(As on option, you could go from Nakusp up the side of Arrow lake and use free ferry to Shelter bay and Revelstoke. then highway 1 to Golden. It is a stunning drive but there are narrow snowshed tunnels on route 1)
Redstreak campground Radium Hot springs. FCFS, $40.75/nt, water 50amp, dump. Excellent brew pub in town. would stay again.
We took route 93 to Banff to avoid roadworks on route 1
You must purchase a park pass to stay in any of the Alberta parks or campgrounds
Banff Tunnel mountain village 2. MUST BOOK!! $36.80/nt. 50amp, water, dump, flush toilets, showers, bus service to downtown and area, free to go in, $1 return. Have stayed here many times. Loads to see and do, recommend Lake Minnewanka loop. Also short trip to Canmore for the Grizzly Paw brewpub, probably the best we have found.
Following sites and prices include fire permit. That includes free firewood but an axe is advised.
Lake Louise campground $37.38/nt. MUST BOOK! Worst site we stayed in, 50 amp but long walk to showers and a working toilet. Absolutely no maintenance to facilities. Area is stunning, avoid Lake itself but get up early and drive to Morraine lake, and take the short hike to viewpoint, you will not be disappointed. If you don't get there early you have to use the shuttle which is extortionate!!
The Icefield parkway is an absolute must do, we would also recommend the drive through the Bow valley parkway for the scenery and good chance of bear.
Silverhorn campground North of Bow summit $28.2/nt Large pitches but only 2 FCFS sites so strongly advise booking. Pit toilets, no water but available at Waterton Lake campground as is dump. Would definitely use again.
There are several campgrounds along the Icefield parkway but few have pitches large enough for 30ft or longer units.
Must sees on parkway, Peyto Lake, Columbia Glacier (tour available but pricy) Athabasca falls, Edith Cavell Mountain
Whistler campground just outside of Jasper, superb but books really quickly, we couldn't get in so booked Wapiti campground $40.80/nt. Flush toilets, showers, water and dump. Either campground is ideal for the area. Jasper is my favorite place, good dining and drinking, laundry, liquor stores etc. If you have time, thoroughly recommend the drive out to Maligne lake and back. We've never failed to see bear on this road and have also spotted moose. The lake is awesome and boat trips are available, so is canoe hire.
Sorry this is so long but hopefully it might help. If you want any further help, send a PM so I don't have to bore all the other good folks here.
We also travelled to Edmunton and further East, but I don't think you will have the time. We've never done Sylvan Lake, but i do know folks on the forum who live near there.
Good luck