Go to Stockholm ! ( my hometown)
Stockholm meets all your requirements. Stockholm is europe's most beautiful capital. We have plenty of water and islands that you can boat hiking to. Plenty of historical buildings and museums to visit. All Swedes speak English, and all are service-oriented. Hotels in all price ranges. You can travel cheaply to Barcelona with
http://Ryanair.se from Skavsta airport or a bit more expensive from Arlanda airport.
http://beta.stockholmtown.com/en/
