The city where I lived for a while and that I enjoyed a lot because it has a lot to offer.
Den Haag is the city where the Dutch parlement is located. If you are interested in the Dutch parlement you can book a guided tour around the ‘Binnenhof’.
If you visit Den Haag on Monday, Wednesday, Friday or Saturday you can wander around the biggest market of The Netherlands, ‘de Haagse Markt’.
For a real holiday feeling I would definitely have a walk at the beach (‘Zuiderstrand’) and the nature reserve ‘Bosjes van Poot’ and finish the day with a drink at one of the beachbars.