moving from Ottawa to Vancouver

Hello there
finally I've got the plane tickets, I will land in Montreal then and after 3
weeks I will take the plane from Vancouver back to Italy.

I would like to spend about one week in the Ottawa area and the last week in
Vancover, I've friends in both cities.

Now I would like to know what can I do while moving from Ottawa to
Vancouver, I mean, I've one week and I would like to visit some cities,
Toronto it's ok but Calgary and Winnipeg too...

- which one is the cheapest way to move around ?
- Is there any very low cost fligh company that makes domestic flighs very
cheap ?

I could even rent a car and stop wherever I like but it seems I will spend
most of the time only driving...

Any Idea ?

Thanks, Davide.