Are stores and restaurants closed in Spain on May 1 for International Workers Day?

Being the original poster I thought I would provide some new info for those who read this: I asked a host at my hotel in Bayonne, he said here in (at least this part of) France that ‘everything will be closed, even the buses’, but restaurants will be open. And he further said that in Spain it is ‘not the same thing’ and that places are more likely to be open on May 1 in Spain than in France so it may be a good day for a day trip to San Sebastián by train.

Here in Barcelona, we expect a lot to be closed - for example, El Corte Ingles is closed across the city - but you may be luckier with restaurants, as the ones that are open do brisk business on holiday-closure dates. If there's anywhere you particularly hope to eat or shop, I'd give them a call just to check - but know that there will definitely be some bars and restaurants that are open, because we all have to eat somewhere!

Most shops, supermarkets, banks...will be closed. There´s no reason at all for bars and restaurants closing, it´s a great day for them, lots of people will eat out. Donostia-San Sebastian will be packed, manage your itinerary wisely!