30, my family did the exact trip you're thinking on. We went the last week of July, first week of August if I remember correctly. Badger is right about the sunlight. Very hard to get used to in the summer. I've never been there in the dead of winter but the dark must be equally if not harder to get used to.
We flew into ANC, stayed overnight in town, rented a motorhome and hit the road for two weeks. We started out south, touring the Kenai Peninsula and visiting friends. The Sterling Highway leads to Homer. I would highly recommend a halibut day trip with Homer Ocean Charters. They are based in Homer, of course. Homer is like a California party town in the summer. Tons of shops, bars, restaurants, fishing, etc. I also recommend the Alaska Sealife Center in Seward, also on the Kenai via the Seward Highway. You could also get a charter to fish one of the big rivers, but I don't know when certain fish are running. Girdwood is also cool and I highly recommend the cinnamon rolls at the bakery at the base of Mt. Aleyeska. The Wasilla/Palmer area was/is really booming, the fastest growing area in Alaska, for better or worse. This is where the "major" highways seperate, with the Parks going West/North and the Glenn going East/North. We have a small piece of property north of Wasilla. Don't know if we'll ever live there or not.
In Wasilla there is the Iditarod headquarters and associated dog sled tours, on wheels in the summer. Pretty fun and different but also "touristy". On the way to Denali, sort of, is Talkeetna. This is really a cool place, some shops/restaurants and the traditional take off place for planes dropping mountaineers onto "the Great One". Really a nice spot. Denali is a must see, if the mountain is "out". I think it is fogged in 90 % of the time. But, in the park, I would recommend the day long bus tour. It's booked WAY ahead so you might want to start checking on it now if you're going this coming summer. It is an all day ride to the end of the road in Denali. You can't drive your own rig in the park, except for a short ways so if you really want to see the grandeur and wildlife, the bus is the way to go. Also the rangers' sled dog training tour is pretty cool.
Fairbanks has lots of stuff to do as far as tourist stuff, such as the few that Badger mentioned, as well as downtown shopping, etc. The pipeline is pretty unique as well and if you come back down the Richardson Highway, the road is very remote, generally following the pipeline. You'll see plenty of moose along this stretch generally and there are lots of spots to stop and fish. The Richardson leads you back to the Glen and back down past glaciers and awesome scenery and on into Anchorage.
I could go on and on, but suffice it to say: "GO!" You will remember it forever. There are even some caribou seasons open in the summer, but I'm not sure on access to those areas. I would think that the bugs would drive you nuts on the tundra that time of year, though.
Good luck and have a blast!
Merry Christmas.