RS's book on Spain doesn't mention Valencia. Is it worth seeing? Can you recommend hotels? Is there a train or bus from Granada to Valencia?
I like Valencia a lot....big and modern like Barcelona, but more Spanish "soul" than Barcelona. It's a little off the Barcelona-Madrid-Sevilla axis, so that's why it probably doesn't get a mention in Rick's book...but check other books, they all have it. Great beaches, a nice combination of modern buildings, old Moorish forts, and baroque churchs....and a very active nightlife! But if you do want to visit Barcelona, it's quicker to get there. Both vueling and Clickair fly Granada-Barcelona in under 90 minutes.