My problem is that I have loved pretty much everywhere I have been on holiday - I must make good choices... So I have many places I would recommend. But here's a few of them anyway.
Croatia - with the beautiful Istria, Dubrovnik and the islands. We went there for 2 weeks and it was far far far too short!
Spain - Catalunya: you have the wonderful city of Barcelona (possibly my favourite city ever), the Pyrenees mountains and the beautiful coast of the Costa Brava, with links to artists such as Gaudi and Dali.
Scotland - Western Isles