DD1, DH and me 'did' the Rockies a few years ago without a tour company. We flew into Toronto, had a few days there including a day trip to Niagra booked from Toronto bus station. Then cheap internal flight to Calgary, few days there, hired a car, drove to Banff spent a day lazing in hot springs and a day at Lake Louise. Drove to Vancouver over two days with an overnight in Kamloops and various meal breaks at tiny villages en route. Dropped off car in Vancouver and had 4 days exploring by public transport - water bus, ferry, bus and sea plane. Absolutely fabulous in all ways and at minimal cost (tween season 15 days spent under £2,000 for 3 adults including flights from Glasgow) because everything is MUCH cheaper if you book IN Canada instead of before you go. We mainly stayed in travel lodge style suites with small kitchen - booked one day ahead from a brochure.
We were a bit worried about going 'freelance' but no way could we afford the package prices and DD shared the driving & did the bookings, car hire, etc for us all. It also meant we could linger where we liked and go slightly off the beaten track, look for houses built by DH's grandfather in the 1920's, visit a school friend. Would love to go back but have to accept it was 'once in a lifetime' and we do have 200 + photos.