Luis , Thanks to your suggestions.
I ended with 4 hours bicycle tour :-)
Bus tour I took first was not worth it ..
Walking tour is good for sure .
Most of the central tourist things seems for me to be within walking distance ....
Take a look at a pano of Holocaust Memorial
http://www.viewat.org/?i=en&id_pn=2154&rc=1&sec=pnregards
BTW,
Berlin is really great city for photography , even police seems friendly, calm and educated .
No one shot at me despite using terrorist weapon of choice - tripod ...
( I have really bad experiences from London , New York and SanFrancisco )