By the way Mankie, I have been working for over one year in the british caribbean and I am starting to follow cricket, at least the world cup, might even be able to see a Super 8 game in Guyana.
Sparx, I welcome criticism of Barcelona. Actually, I have been living abroad for the last nine years and everytime I return home I am bit disappointed. Barcelona is now a city designed for tourists and it is almost impossible to have a coffee in an old square in the gothic neighborhood without having to see thousands of people. Nothing against tourists, it is great to see so many visitors enjoying your hometown, but I think the city is losing a bit of its charm. I guess it needs to find some balance between tourism and the residents in the city. For example five years ago there were no direct flights between the US and Barcelona, now you can find direct flights from JFK, Newark, Philadelphia and Atlanta.
Anyway, back to the topic, I cannot recommend about beaches in Southern Spain, but I will ask a couple of friends form Andalucia to see if they can recommend nice beaches there. As Rhett said, in southern Spain you may also want to visit Sevilla and Granada and if you are coming from Madrid, visit Toledo as well.
However, for nice beaches in Spain, I would also consider Menorca in the Balearic Islands, in June it should be quiet and you should have a very nice time in some excellent beaches.