Couldn't find an entry for this place, so I figured I'd post it here.
Just came back from our Alaskan Adventure. A big chunk of it was driving from Anchorage to Whitehorse, seeing Valdez, driving both roads in Wrangel St. Elias and Haines on the way. 2000 miles in all!!
On thing that made it all worth while was the fact that I discovered the Go North Alaska car rental. They have offices in Anchorage, Fairbanks and Whitehorse, do one-way rentals, let you take the car on a ferry (we went from Haines to Scagway) and on any road you want. We had a huge 4-wheel drive and used it on the Mcarthy and Nabesna roads.
While they are expensive, if I compare the rates to the rates at Avis in Kodiak for a tiny car, it's comparable and you get so much more, and besides, when I divide it by 4 (there were 4 of us), it's comparable to plane tickets, and you get so much freedom.
They also have great customer service and the vehicle was perfect. Alaska is made for road trips, and this car made it so doable!