The Maurithuis (to see Girl With The Pearl Earring) is an EASY museum to visit and enjoy. A couple hours and you've seen it all, and in very pleasant surroundings. That would be my primary attraction.
Delft, where we stayed for several days last year (and side-tripped to Rotterdam and the Hague) was lovely and a nice home base for day trips - often on bike - as well as some nice places to eat and drink and relax. Tourism wise, Delft gets 20 pages or so in the RS guidebook, and has a walking tour (which we did). There is plenty of non-essential stuff to do there unless something very specific is one of your interests.
Coming off a cruise, where you will hopefully have eaten well and gotten some time to relax, I think the Hague is a nice speed to get you ready for a return home. Of course, the flip side is that the cruise may have been museum and city-centric, so maybe a visit to Delft and some slower paced activities might make more sense for you. Since you will be passing Delft on the way to the Hague, it would be back tracking, so maybe instead, from the Hague, a trip to the coast and Scheveningen would be fun.