Medialab Prado is the coolest place to work, to collaborate, to do workshops, to participate in events and conferences. They are the nicest people in the planet doing such interesting programs. My favorite is Interactivos. It is also a good place to meet new friends and go afterwards for beers in the bars around Lavapies, a district full of art galleries and Museums.
A bar and bookshop to enjoy a glass of wine while reading a book or to read a book while drinking a glass of wine. They show a careful selection of contemporary literature and artworks downstairs, from where you can spy on the people upstairs because the ceiling is made of glass.
Spanish artist Jaime Hayon is sometimes called Almodóvar of design. So if you like "Kika", colours, Spanish culture and dreamy aestetics, you must visit Barceló Torre de Madrid and stay there for a night or just have a drink in a golden bar.
A piece of Egypt in the city centre. This temple, a gift from the Egyptian government, was taken stone by stone from the valley flooded when the Aswan Dam was built. It’s a great place for a picnic in the summer. You can enjoy the sunset and the (grey) skyline of Madrid.
Reina Sofia museum is always a good idea. And it's never enough of Picasso's Guernica as well as the other modern art gems. Save some hours for visiting and then look round the corner and have some wine at NuBel.