best place is south of Spain (andalucia).
Cultural/cities: siviglia, granada, cordoba
Beach/entertainment: you have just to choose....
By the way my favorite is norht of Spain, you can find similar things but clima is warmer.
i'd second daisan's sugg of andalucia! i've never been, but i've been reading up on the region for my upcoming trip in april and i cant wait to go!
Well two weeks is a limited time frame but you can still see a lot of Spain! My advice is to go for a view days to Barcelona because this city is amazing.
You can do so much things here in Barcelona like; sightseeing all the monuments, going to great clubs at the beach and in El Borne, there are a lot of bars and restaurants for each budget, shopping off course, there is a beach here and if you take the train for example to Lloret de Mar it is only around 6 or 8 euros ( for a round trip) and the beach over there is so much better and beautiful.
You can also go the an attraction parc in Barcelona Port Aventura, or do a walking, bicing and bustours through the city.
I promise you that you won't have any regrets with coming to Barcelona for a view days and from here you can go the Madrid, Malaga, Valencia etc... by train or plane. Just book your tickets in advance because the tickets are much more cheaper then.
I hope I could help you and if you need more information just ask!
p.s. Have a look on this blog there is a lot of information about the Barcelona city http://www.oh-barcelona.com/en/blog/