Agree with prioritypress - goodview is good food and music, as is riverside.
Three days isn't alot in Chiang Mai - two days walking around the city...In the evening there's a night market, also on a Sunday there's the Weekend Market.
Wat Phra Doi Suthep for a great view and chille out temple.
There's a lake about 15 mins drive from centre of the city where the kids can swim and you and famiily can get a hut on the side and stuff your faces. Ahaa here's a video
If you can ride a motorbike and can escape there are some great tours which will take you off road up near the Burmese border, also a small chinese village.
Other than that there are no end of beautiful gardens etc. and of course food and genuine smiles everywhere.