4 full days in london, paris, rome and 3 full days in berlin sufficient??

im thinking of going to those places in a few months, i have been spending a lot of time reading stuff and have come to the conclusion that those days would be sufficient to fit things in...am i on the right track..i pretty much want to see the major tourist attractions in addition to doing a little bit of shopping. i love museums, but dont want to spend my days constantly in one. so the lourve appeals in paris only.. in terms of museums, if i can do one in each country that would be fine..im more into walking and seeing sights. suggestions would be very helpful. thanks.