I've done Benicassim the last 2 years. The line up this year is pretty grim which meant I went T in the Park. T is probably the best of the UK festivals i've been to, defo need to do Glastonbury.
When I went Benicassim first year we stayed at a town called Alcosebre which was miles away from the festival, absolute ballache to get back. We ended up paying this random bar owner to give us a lift back every night, until the police busted him. 2nd year we stayed at Castellon which is one bus ride away from Beni, decent town as well defo recommend there, the hotel we stayed in was cheap but fairly good. Taxi drivers are feckin useless over there!