If you like street art, Berlin is like a free outdoor museum dedicated to the medium. Take a stroll down Kopenicker Strasse in the east part of town and you'll be in the thick of it. Look out for the paper cut outs applied to surfaces. Sadly, ugly tagging tens to cover a lot, but it's color adds to the overall impression.
Oderberger Strasse is one Berlin dreams are made of: It's two ticks from Mauerpark, full of gorgeous buildings in all the colours of creamy gelato, and stuffed with quirky shops and great pavement cafes and restaurants. If you're going to stay anywhere in Berlin, stay here.