In reply to rockcat:
Don't forget the slate. That has probably the biggest numbers of lower 6s and low to mid 7s in close proximity.
Also Penmaenbach is worth a visit. I think all the 7as have now been downgraded to 6c+ so maybe no 7s left there now but some good lower 6s and an excellent 6c+ (Map of the Problematique). Also it is not far to Noticeboard for a recommended 7b.