I was in Berlin 2 years ago for the Berlin to Budapest tour. Since you have extra time there, you might wanna check out the Sachsenhausen Concentration camp..great place of history though it got me a little depressed :p you can also try Berliner Dom, i missed it but I heard it was gorgeous inside...Schultheiss for some delicious curry wurst but bear in mind taste is subjective.
Then there is the Brandenburg Gate, the Holocaust Memorial and of course, the Berlin Wall...hmm..is it still there....anyway, have a blast!!
Thanks so much for taking the time to help me, it's much appreciated! I'll be sure to look up all those things, and I love bratwurst and am pumped to get over there and try more types! Thanks again, take care!