Driving it 5 times round trip between Kodiak/Anchorage/Juneau to/from both Michigan and Virginia.
I've traveled it round trip 6 different times. Twice in the winter. Once by Ural sidecar motorcycle. The other 3 times in various modes of transportation. Length depends on where you're starting from, and how much time you wanna put into it. Quickest I've done was Anchorage to Sault Ste. Marie, Michigan in 6 days. Very hard driving and no sight-seeing. Not cool. Plenty of places to stop along the way. I never carried any gas UNLESS I was planning on venturing off the beaten path.
Get a NEW copy of "The Milepost" - that thing is worth it's weight in gold. They update it each year and it's invaluable as a planning tool. Mile by mile descriptions of all the major highways that are very detailed. Includes gas, restaurants, hotels, campgrounds, sightseeing stuff, etc. Double check when the new edition comes out (I wanna say May of each year).