We visited in '04 and totally agree with cbalaska's comments.
The Midnight Sun is very deceiving. Many times we were out and before we
knew it, it was already 9 pm and we still had not eaten dinner. There were
quite a few times that we were driving around after dinner, just enjoying scenery, and next time we knew, it was around 10 - 11 pm and we were
not tired. Very deceiving with the bright sky around. We had to force
ourselves and our kids to go back to the hotel and really close the curtains
in order to sleep.
Another comment about the drive up to Denali from Anchorage - there
are lots of little neat towns along the way. We did stop at Talkeetna
and thought it was a cute, little town.
Stop by at Mile 147 to see the Veteran's Memorial.
Between there and back to Anchorage, we found a little pizza place called "Angela's Pizza" owned by a German woman who runs the entire place by herself. Great pizza, and very inexpensive.
Have a great trip. We really enjoyed Alaska.