Are you looking North or South? I don't know the South Cotswolds well, but if you're looking at the North, I have a sentimental attachment to Chipping Campden (went to school there, and married in the very beautiful church). There are nice walks around, and pleasant tea rooms.
Another option is a walk around Broadway Tower.
If you have children, I'd go for Bourton on the Water. My DC are now young adults, but have happy memories of paddling in the river, and visiting Brum and the model village.
The Slaughters are nice, and have a good circular walking route.