I was born in Wales and used to go back there occasionally until a couple of years ago - we frequently had some astonishingly bad food, and saw even worse that we didn't risk. Ridiculous given that you can get some of the best meat and fish in the country there.
Anyway, enough negativity. If you're up at the other end of Wales, the Ship Inn at Red Wharf Bay on Anglesey is well worth stopping at - good food made from local ingredients on the whole, good beer, fantastic views out to the sea and to Snowdon and a couple of cheap B&Bs next door. Good bit of walking nearby (or driving) and a huge amount of history.
http://www.shipinnredwharfbay.co.uk/
Can you recommend anywhere good in South Wales that's a bit more remote than Swansea - good hills or good coast, somewhere where you can eat?