Wife and I honeymooned there.

Take DEET. Not the usual10, 20, 30, or 40% DEET. Start with at least 70% DEET. Be careful in what you touch with DEET on your hands - DEET is an excellent plastics solvent.

The mosquitoes in Alaska a huge and hungry. In Alaska, folks like to play a game: You flatten out your hand and then slap your buddy on the back. You then count up how many mosquitoes you just killed. We were told the record is 28 in one slap.

One thing we recommend is to take the Alaska RR train from Anchorage (or south) up to Fairbanks. Alaska RR also runs the last flagstop train in the US; it is  possible to flag down the train and take it from place to place along the rail on certain stretch. You just need a big red bandanna, stick or rifle, and a long enough straightaway that the train can see you a fair bit ahead.

The observatory in the University of AK's Fairbanks campus has a good planetarium and lots of information about the Northern Lights.

Oh, one other thing: After Labor Day, lots of Alaska shuts down in a couple of days. By the weekend after Labor Day, maybe only one-quarter of the tourist stuff is still open.