The Canadian section of the Rocky Mountains stretches for nearly 1500km from north to south. There are certain things you should keep in mind when traveling in this vast, wild part of the world.
While the towns of Banff and Jasper are well connected, the rest of the area is wild. If you're looking to go hiking in the parks for more than just a day trip remember that you're entirely responsible for yourself. Always pack out any garbage that you pack in, and make sure that you're registered with the park if you're heading out into the back-country.
ATM's and supplies, post, laundry services, etc are available in Banff and Jasper. Accommodation is fairly available, with many rustic cabins available for rent, and of course the large hotels of Banff Springs and Chateau Lake Louise. Camping is available at various sites and pre-registration with the park is recommended to reserve a site during the peak summer period.
As far as weather is concerned, snow can fall as late as June and early July at the higher elevations and weather generally changes quickly in the mountains. On one side of a mountain it could be sunny, and on the other it could be rainy. Bring clothes for all weather conditions. Even in the summer it can get cool in the evenings especially so bring a sweater as well.
Wildlife is very abundant in the Canadian Rockies. Always be mindful when you're hiking and never go out alone. Check with the park offices about the latest bear sightings and read the wildlife page for more information on how to avoid any problems.