We did a really quick Morelia trip after going to Chapala this past weekend. It was nowhere near long enough, but we're planning on going back soon.
I loved this city so much. Vallarta and the Pacific Coast seem to be the most popular places for expats to go from Guadalajara, and it's nice there, but I think it's much better to go east to Guanajuato or Mexico City or Morelia. They're so much more interesting and the weather is always better.
We drove in on Sunday morning when the main road in front of the Cathedral was closed for biking so we walked along with everyone else. We went back the next day for a bit before we needed to leave.