Not sure I can provide any information without knowing what your conveyance preferences are and what travel limitations might affect you, age of children or mobility of grandparents. How many days can they deal with? Alaska is not a foreign country, so things are relatively easy.
But are you speaking of cruising the Southeast and never getting off? Or are you looking for some kind of combination of cruise followed by train, plane, car or bus from Anchorage? Focus on National Parks? (If so, which ones?--Glacier Bay, Kenai Fjords, Denali, Wrangell-St. Elias?) Do you want to go to the extreme north, Fairbanks and beyond? Fishing? Camping?
Cruising the Southeast is absolutely beautiful--but, in a sense, the sights are the same. Plus, towns like Ketchikan, Sitka (well-known for its summer music programs and Russian dancing; amazing auditorium), and Juneau (Mendenhall Glacier and fun waterfront) are all relatively similar. Juneau has a Gray Line tour; the other two are walkable. And throughout the state, Gray Lines is a travel power behind the scenes, so you might start with their website. Westours and Holland-America all have connections to Gray Line.
Designing your own itinerary can be worthwhile if you take the time.