The Milepost, mentioned by
above, is the essential tool for the trip. Buy it now, and read it. Your Navigator should read it as well. Then you can plan your trip much more intelligently. In addition to Hannibal's excellent ideas, here are a few more:
Laird River Hotsprings.
The Bakery in Haines Junction.
Museum of the North in Fairbanks.
Whitehorse -- drive down to the visitors center. Steamboat is fun and you will want to walk around.
Consider taking the Cassiar Highway on the return trip. It has beautiful scenery and you are almost guaranteed to see a black bear.
is an informative map of Alaska in pdf format.
Drive the Denali Highway between Cantwell and Paxon. At the east end are the Tangle Lakes with a nicely improved campground from the old days, and the roadhouses along this highway are emblematic of the old style roadhouses, most now destroyr=ed by fire.
In my view, after having lived in Alaska since 1976, the Richardson Highway is the last remaining highway that gives you an idea what it was like to live here in the days immediately before the pipeline brought so much change. Glennallen, Copper Center, and so on will let you know you are NOT in California.
Drive over Hatcher Pass and visit the mines at the top.
Stop in at the Bakery in Girdwood. The bakery at the junction of the highway is fine, but the cinnamon buns at the Bakery in Girdwood itself is much, much better.
The best biscuits and gravy in Anchorage are at the coffee shop at South Restaurant on the Old Seward Highway.
Fenton Brothers for fishing on the Kenai. They are great guides and hilarious. Mike and Murray have been doing this for decades.
If you are a foodie, stop at Froth and Forage on the Seward Highway near Indian. You can't go wrong with anything on the menu, but their poutine is a belly buster.
If you want to go up to the Yukon, you can drive up the haul road, in which case you will stop at the Hilltop restaurant for pie and the obligatory bumper sticker. Or you can drive up the Steese and see it there, plus there is a chance to drop into Circle Hot Springs, now a fading memory of what it once was.
There is so much more. After you read the Milepost, you will see what I mean.
A final note. In mid-summer, all the fuel stops are open. You should not need extra fuel, even on the Cassiar, if you utilize your CPU and keep an eye on the fuel gauge. My rule of thumb is before leaving a population center, I look at the fuel gauge and assure that I have more than enough fuel to make it to the next major town. I travel with no more than 4 gallons in a rotopax. even at the 15 mpg pulling a trailer, that gives you 60 miles. However, if you do go North of Fairbanks to see the Yukon, carry at least that 4 gallons.
Avoid the Coal River Campground. The food may be good, but the shower rooms are, uhh, yucky.