I have been only to York. The visit to the cathedral was alone well worth the visit. Take the guided tour to get the most of it and learn the rich history. Then walk the wall around the old part of the city. A full day. We loved it.
Pictures of our trip are here:
{Starts with picture 205 and forward from there}
http://picasaweb.google.com/AnesMerc...27991108798754