Llangollen or Langdale both appeal, they both are great places. Personally I'd prefer Langdale simply on the grounds that the Lake District mountains are more interesting walking than the Berwyns or the Clwydian hills. But I'll go with the consensual opinion. There should be B&B's, or self-catering accommodation in both places for those who can't stand the thought of dormitories.
Thanks Geordie for starting the ball rolling on this.