Hello, I'm from Germany and not too fond of Berlin, but that might just be me personally. I heard it's amazing for clubbing if that's your sort of thing and of course there are tons of things for history fans (museums, mostly). I'm just not sure if five days aren't a bit too much (but then, I hardly ever stayed anywhere for more than three nights in a row except for London). You could look at hotels in Mitte, try to avoid Neukölln (high crime rates).