staying with friends in whitehaven in northern england. should we go to Alnwick Castle and another one nearby, or Hadrians Wall? or York? suggestions on things to see in this area?
It depends on how much time you have. I would do all three. Alnwick is a beautiful castle, the first parts of it built about 1096, used as a location for many movies, such as "Elizabeth" and some of the Harry Potter movies. York is a "don't miss it" site, with the old city walls and York Minster. Hadrian's Wall will not take as long to see as the other two. Maybe you can do all three. I would try to.
I assume if you are staying with friends you are there for at least a few days. I would agree- see all three. York would be my priority you are also in a great location to see Lake District and Chester (Chester is a great little town with walls and Roman ruins which is not on the radar). Also just for kicks how about visiting gretna Green just over the Scottish border