Are you doing the pre-cruise by yourselves, or with Princess? If the latter, they will have excursion choices in Talkeetna and Denali. I definitely recommend a wildlife tour in Denali (it should take at least 1/2 day)! The buses stop for virtually all wildlife sightings, whether close or distant.
$45 a night is pretty cheap for Anchorage, but not unheard-of.
What to see/do on the cruise? - scenery, wildlife, glaciers!! Again, the cruise line will have many excursions offered. The Alaskan ports are small, so if you don't want to do whale-watching or float-plane sightseeing or glacier hiking or fishing, you can walk through the town and simply enjoy the sights, history, people, etc. No language barrier!
Enjoy! It's one of my most favorite places!