Hard Rock Cafe at the airport offers a comfortable workspace with fast WiFi and a decent food selection, including affordable coffee. It's suitable for extended stays, with tables readily available and staff accommodating.
Despite being a restaurant, this is a great place to work at the airport. The coffee is cheap and decent enough (€2 for an espresso). I've always been able to find a table (this time I sat at the bar). And they expect people to be killing time and spending a while here so the staff are okay if you hang around for a few hours. There's also a screen with departure info visible at both ends of the restaurant. You can use the airport WiFi and it's always been fast and reliable for me.