Barcelona gets anbother vote form me. There are plenty of hotels to choose from and I recommend the L'Example district or Barceloneta. The Gothic and Las Ramblas areas are good to visit but too busy and noisy to stay in.
Check out all the Gaudi sites, especially Parc Guell and Sacrada Familia, go up to the Mountjuic or spend a day on the beach. Its in my top 5 places to stay.
Don't be put off, but do beware of pickpockets. We were pickpocketed even though the pocket was inside the coat and zipped up. Thankfully we only lost a few quid, but leave passports and half of your cash in the hotel safe. Don't take anything you don't need - just one credit card, no drivers licence etc and spread stuff about your person.
The metro is really easy, the restaurants and hotels are plentiful and the weather is perfect in the spring.
My next favourite place is Amsterdam. Been there?