Periscope (22 Haritos St; yeshotels.gr; room from €149) Award-winning minimalist hotel in Kolonaki district - check out the slide show of the city on the ceilings.
Kalderimi (Plateia Agion Theodoron, on the corner with Skouleniou, Monastiraki; mains from €5-8) Freshly cooked, authentic Greek cuisine. In a city full of tavernas this is one of my favourites.
Benaki Museum (Koumbari 1; benaki.gr; €9) Outstanding private collection from Bronze Age to WWII in what I think is the best museum in the whole country - there are two other branches, the Pireos Annexe (contemporary art) and the Museum of Islamic Art in Kerameikos; a combined ticket for all three costs €20 and is valid for 3 months.
Gazarte (Voutadon 32-34, Gazi; gazarte.gr) arts complex with a cinema, incredible views of the Acropolis, the odd live music gig and even a restaurant. Not bad for a bar!