Heritage Museum, St. Petersburg
Le Louvre, Paris (+ Orsay)
Del Prado, Madrid
Anne Frank House (during peak times, more like a pack of sardine than actually visiting a museum) + VG Museum (too pricey + commercial) + Rijkmuseum (LONG queues)
Honorable mention: London is a wicked city with MANY good museums for us aficionados - 2 free galleries about paintings and portraits, one BIG museum about history, one interesting one about warfare, one about modern arts(Tate Modern), two about traditional arts(V&A,Tate Britain). I reckon one week isn't enough.
I am gutted I didn't go to Kelvingrove when in Glasgow