If you're looking to travel from Calgary to Jasper to Vancouver, the best option is to rent a car. While it may be pricier than other modes of transportation, renting a car will give you the flexibility to explore at your own pace and see all the magnificent natural features along the way.
The journey from Calgary to Jasper is about 5-6 hours, and from Jasper to Vancouver it's about 8-9 hours. Be sure to factor in enough time for pit stops and exploration!
If you have more time, consider extending your stay in any of the locations on the itinerary to see more of what they have to offer. If you have less time, you can remove a location to make the trip more manageable.
Additionally, packing comfortable clothes and shoes is a must for this itinerary as you'll be spending a lot of time outdoors. Be sure to bring along a camera to capture all the breathtaking views!