Bart
My first recommendation is to stay 3 nights. One night in Dornoch is like having a quickie with Catherine Deneuve. Three nights is more like starting an affair with a young Catherine Denueve. However, if you must......
.....try the Dornoch Hotel. It was once a railroad hotel equal to Gleneagles and Turnberry, and the class still shows through in the grand staircase and the wood panelled bar. They have family rooms, which are unlikely to be taken as the bulk of the current clientele is pensioners. The first tee of the golf course is only a John Daley drive away, and along that path you'll pass a scruffy pitch and putt that can entertain you and the family in the gloaming.
Rich