If you like trains, an absolute 'must-do' tour is the White Pass Summit train on the White Pass and Yukon Railroad (WPYR) based in Skagway.   The scenery is fantastic and the trains are great.

While in Skagway, you can wander to the train yard (and this will let you see Skagway from one tip to the other, quite literally).   It is a good walk to work off your breakfast and you will probably get to see many of the train consists being run by the WPYR along the way.

Unless you are are just stopping in Anchorage as a quick in-between on the way to somewhere else, you will probably want to rent a car to get around to see things, there isn't much to get to by foot.

If you want the convenience of walking to restaurants, pick a hotel in the midtown area.  Downtown Anchorage has some restaurants, but they are spread out a lot from the hotels.  And there are more hotels in midtown.

An absolute 'must-eat' place is The Moose's Tooth in mid-town Anchorage.

If you like old stuff (cars, trains, electronics, planes), a nice place to stop is the The Museum of Alaska Transportation & Industry off of Parks Highway (mile 47).

It has neat stuff to see in a very relaxed environment with very friendly people (and the occasional adorable rescue animal you can adopt).

The water is teeth-numbing cold from glacial rivers.  So, be sure to check that you have hot water before the front desk closes.
 
And, since the cold of the water radiates up through the porcelin in the toilet, leave the toilet seat and lid in the up position so that it doesn't get very cold and give you a shock in the middle of the night.  (I know, we've all been taught to put both down when done, but you'll appreciate not freezing your tukhus off.)