The best thing with Astypalea is Chora: a very clean and beautiful village, one of the most traditional villages in Greece. Beautiful in the day with the sunlight and also great at night with the soft lights that extend from the castle to the port. Beaches on Astypalea are not so great. They are of course clean but too remote. I didn't see any beach bar there. Best spot for a coffee is in Chora, in the cafeterias next to the windmills.