In reply to Philip:
I grew up in the area. If you want a nice day out for a rest, consider a little history‐based day tour around the Machars. Wigtown (Scotland's book town) and the historic market town for cafes and a browse round secondhand book shops, drive down to Whithorn for the priory/museum and out to the coast for a lovely short walk to for St ninian's cave and/or a walk to St ninian's chapel at the Isle of Whithorn (great community owned cafe here too). For some ancient history, you could go via Cairn Holy or Torhouse stone circle. Cruggleton castle ruins from Garlieston is a nice walk, and you can appreciate the WW2 history, where the mulberry harbours were developed in secret.
7 stanes is great, kirrochtree is a family favourite (again, an excellent locally run cafe). If the Merrick is a bit much (depending where you start, it can be a bit of a bog trot), then a walk around Loch Trool from Bruce's stone (with the Robert the Bruce history) is another family fave.
Have a great time