In the past few years Alex’s crew has done events not only in Spain but also London, Dublin, Paris, Amsterdam, Budapest, Prague, and probably others I can’t recall offhand. I think that’s casting a pretty wide net. And to be fair, Barcelona was one of the original iGaming conference hubs. It’s just a really appealing place to get together.
Spain is also probably more of a focus these days because it’s one of Europe’s larger markets and some big regulatory changes are happening there:
http://www.onlinecasinoreports.com/news/industrycoverage/2011/5/26/first-online-gambling-license-issued-in-spain.php