Earlier in the year I asked AB'ers for recommendations regarding small campsites on Anglesey.
We stayed for a week at Mount View near Amlwch, a superb little site in the north of the island.
Anglesey was recommended by quite a few people but we found it the most boring place on God's earth. If you get good weather and have kids I suppose you could have a good beach holiday, just don't stay in the north of the island, even more boring.