I've just come back from wales, visiting a friends family, I'd never been before, despite only being in England, but oh, it was lovely! I went to the city of Cardiff, and it's very beautiful, such friendly people, with great accents!
I went on loads of bike rides around the several parks (got a sore butt and aching legs!), visited the castle, museum, and of course did some shopping.
I'm sure whichever you choose will each have its little adventures, have fun!
Instant karma's gonna get you.