Thanks heaps for advice, it's truly appreciated. We have started looking into some of your suggestions .On the way from Calgary to Vancouver you will be taking the Trans-Canada Highway. First off Calgary can be fun but it's mostly just the drunk kind of fun. After you wake up from haze feel free to make the hourish long drive to Canmore. While there I suggest checking into the Hostel Bear, probably one of the nicest hostels I've stayed in. Within stumbling distance is the Grizzly Paw Brewery. Very nice beers with decent pub food. Canmore locals are also very nice and if you're looking for more fun I'm sure striking up a conversation with anyone would not prove fruitless.
Next on your list in Banff, obviously. As an Australian you are bound, by law, to stop at Banff and flirt with some fun-loving Canadians. Apparently your accent is very appealing. I would suggest staying at the Samesun. Not only does it have the cheapest bar in the city but it's also full of other young backpackers who are looking for a good time. While in the area you can check out some very nice hiking trails. Maps and very friendly Park Guides are available at the Banff Visitor Centre which is right on Banff Ave. Approximately, a four minute walk from the Samesun. Unfortunately for you, the end of April is considered "high season" so if you do want to stay here you had better make a reservation. Also while you're in the area feel free to try out skiing or snowboarding as pretty much all the resorts stay open until May. Sunshine is the best price for the best snow.
When you leave Banff you'll head on to Lake Louise. Lake Louise is a very nice lake with a very nice hotel built basically on it. This area is definitely more expensive and I just suggest spending a couple hours here. Which you should spend hiking to the Lake Agnes Tea House. It's about 3-4km hike there so bring water and a snack (preferably something with protein in it). If you find you want to stay in Lake Louise, get yourself to the HI. HI of course stands for Hosteling International.
After Lake Louise you will take a sharp turn West and suddenly be out of Banff National Park and into Yoho National Park, which is absolutely stunning. If you don't see a moose at this point you have basically failed at touring in Canada.
Golden and Revelstoke are the next major stops on your journey but since I rarely travel to Vancouver I will let someone from BC explain the rest.
Good luck. Have fun. Don't litter.