When DS was little we had a full day out of fun activities. He was about 4 so we went to soft play with his cousin, out for lunch, to the park. It was all of his favourite things bundled up into one, and at the time going to soft play was an expensive hobby. 
When I asked him what his favourite part of the day was, he was very insistent that the stop at the dentist first thing for s check up was the best thing he'd done all day!