One thing I'd tack on to jackal's reply is that by late August, the fall colors have usually arrived in the Fairbanks area. It's no Vermont, but the hills are often completely golden thanks to the birch trees turning. And Fairbanks does have some pretty interesting things to do, contrary to what the average Anchorage-ite who has never even bothered to go up there would tell you (I used to work with a girl in Anchorage who said she never wanted to go to Fairbanks because somebody told her there weren't any traffic lights there. True story, I swear. She was also a blonde).

The UAF Museum of the North is constantly rated the best man-made attraction in the state, and Chena Hot Springs is a great side trip, especially if you want to take some nice hikes; Angel Rocks is a great three-ish hour loop that's not too straining, and can also be extended all the way to the hot springs if you so choose; the trailhead is around milepost 45 or 50 of Chena Hot Springs Road. I've never done the Riverboat Discovery, but everyone I've talked to about it says that it's fun to do.