Castle Douglas is quite a nice place. Good for local independent shops, much better than Dumfries.
I live in Dumfries and in the right areas it has some good schools and neighbourhoods for bringing up kids. If you have family down south then Lochmaben(10 miles east of Dumfries) is a good place to live. Quite village with easy access(10mins) to M74. The primary school always comes out top in the HMI reports.
If you are after any specifics the feel free to ask.
Keith.