miles driven per day?

Getting across the lower 48 Plains you can do 300-400/day without stopping for siteseeing if you drive interstates. However, once you cross Canada, don't plan on more that 150/day, if that, and if you really want to take in all there is to see enroute to Alaska. There are so many gorgeous places to see in Canada and the Yukon before you even reach Alaska. Most travelers sitesee as they go instead of backtracking after parked. This will drastically shorten your driving miles. Sometimes we even drove 50 miles from one place to another.

Have fun planning - that a fun part of the whole trip.