Did this in 2006. Scenery is spectacular, roads are good. No shortage of fuel/food, but it's all more $$$ between Banff and Jasper. If you have time (like someone else stated above), try to catch Hwy 40 (Kananaskis) through Turner Valley. This will take you right on to Hwy 93 and through the Rockies.
As for getting to Alaska, via Yukon, the roads are in decent shape. The severe winters cause heaving - so there will be some road construction throughout the spring/summer. These can stretch from 3 meters to 10+ kms.
Most visitor centres (in Canada anyway) have free maps and up-to-date road conditions and construction areas.