Update. Last week I stayed for the second time at the QUENTIN Design Hotel, Kalckreuthstraße 12. I tried this hotel a while ago, when the Pope was in Berlin, and this was the only option, West of the Brandenburg Gate, where my work is. Not bad, nice interior, and I paid only 80 Euros. Internet works like a charm and is free. Well worth it. To whom it may concern: the area around the Quentin seems to have a lots of gay bars and adult bookstores, but still not a bad area.