Ok, if you are a party boy then you may end up in partyland. If my calculations are right (99% sure they are) the most happening and crazy party takes places in Madrid on the 14, 15 and 16 of August (be preparared, I recommend dancing lesons at least some merengue). Madrid celebrates "Virgen de la Paloma", that is, the virgin of Madrid and one may well say that this is Madrid only once in a year huge street party.
There will be things going on from the 7th on but the big thing starts on the 14th. Recommendation: go to Almendro st (the center of the huracan) drink and get lost among the thousands of people form different nationalities you will find there. I am going to send MM three pictures of last year party to see whether he can include them in this thread.
Andrés