Sent this note to someone else recently - might be of interest...enjoy!
First of all I would recommend the sightseeing tour to give you a good overview of the city and the sights you might want to spend some time at - I think its around €18 but you can hop on and off as you like. Personally I would go the whole way around and then decide which ones I'l like to spend more time at see here
http://tinyurl.com/5l6tt4
You must visit the Ka De We (that's the short name) [broken link removed] great for retail therapy and fantastic for food on top floors
Great craic and the Hackescher Market where you can eat and drink to your hearts contant - nice spot with lots of young(ish) people
Potsdamer Platz is also well worth visiting - the WALL (or what's left is here) and Checkpoint Charlie is within walking distance
Boat trip down the river (SPREE) is excellent especially if you get good weather (see here ==>
http://tinyurl.com/6ozsa8 ).
A visit to the Parliament building (Reichstag) is well worthwhile (but get there early to avoid queues) Beautiful 360 degrees view to Berlin city - the Brandenburg Gate is nearby and also worthwhile paying a visit to. If you go to the Gate pop across the road to "Memorial to the Murdered Jews of Europe "
http://tinyurl.com/5svm44
You could spne da couple of hours strolling down Unter den Linden - centrepiece of the Old Berlin, leads from Pariser Platz at the »Brandenburg Gateto the Schlossbrücke bridge. Unter den Linden was originally a bridle path: from 1573, it led from Berlin Palace to Lietzow, later Charlottenburg, and then on to Spandau. From 1701, the Linden became more and more built up, mirroring the rising splendor of the monarchy and the new architectural style.
Great views of the city from the Fernsehturm tower.....
http://tinyurl.com/56wzyw
Roy