I spent a few weeks traveling around Spain last summer and I found Valencia to be my favorite city!!
Small, even smaller than Dublin but very clean and well kept. Food is fantastic and very cheap, like most of Spain. It is the home of Paella and (although I did not get a chance to go myself) there are small villages around l'Albufera that make the best Paella in the country. The beach is about 20mins on the subway from the city centre and I found it to be as good as most. I was lucky enough to go see the local derby soccer match between Valencia and Villa Real, even if your not a soccer fan it is still an amazing experience. There is a fantastic museum built in the city but I did not have the time to visit it, I have been told since it is worth a few hours of your time.
It is the perfect place to relax, eat and drink. Try a restaurant called La Pappardella off the main square. Very very reasonable and great food and atmosphere.
Enjoy!