The "ermita" of the Virgen del Rocio is near the town of Almonte, I don't have a map next to me right now but it is possible to drive there coming from Seville. The event culminates in the early morning hours of Monday when the almontenos "salta la reja" or jump the gate inside the shrine in order to bring the statue of the Rocio out, at which time if you are there and are able to get anywhere near it, which is unlikely, you will see brawls beyond the wildest stories your Irish husband could imagine, as people clamor desperately for the right to parade the virgen.
The Rocio isnt really my cup of tea, its loud, festive, crowded beyond belief and everyone is more or less drunk the entire time but it's the andalucian ritual par excellence. At the actual Rocio itself are the houses maintained by the various brotherhoods from different Andalucian cities, I'm not sure about alternate sources of accommodation but I imagine that doing the Rocio would be a day (possibly turning to night) trip. I guess its worth it to see the spectacle of men dressed in the traditional 'corto' riding beautiful horses, the horse drawn carriages, and the beautiful women in their 'gypsy dress'. If you do go you're unlikely to forget it!