According to a recent article published on Time Out London Ibiza is one of the six main reasons to visit in Spain.
In regards of Ibiza town Time Out says:

“The walled town at the heart of the island’s capital is a World Heritage Site, the Plaça de la Vila is packed with elegant shops and restaurants, and there’s a jazz festival at the end of July. There’s a lot of night stuff, too – try minimalist Grial (Av 8 de Agosto, 34 971 31 46 39) for pre-club drinks and then roll on to the Love Club (C Alzines 15, www.loveorganisation.com) until the sun rises and it’s time to go back to the beach. ”

The other Spanish destinations suggested by Time Out London are Alicante, Palma, Barcelona and Malaga.