Unemployment is very high in Spain and is particularly high in the tourist areas out of season, however this should not stop you heading to Valencia looking for work.
The easiest sort of work would be teaching english and working in a bar.
Teaching English is big business throughout Spain as most profressional jobs now require it as part of their requirements in the job. Business ENglish is particularly in demand and you are expected to have a native tongue and an EU passport.
However it is not impossible to get work with an American or Canadian passport as many employers prefer the North American accent.
Bar work is plentiful in the city of Valencia and the English pubs on the Costas, however you should have a good command of Spanish as many Valencians like to frequent Irish pubs.