Hi there, I wish you a nice trip.
I can't help you much with Greece and Turkey, but I lived in the Netherlands for a few months. Therefore, I second the idea of an UWA and TS lenses. While I was there, I ended buying a sigma 8-16mm for my crop body as the streets are very narrow and there is some monumental architecture there.
As for places to go, I'd say Zaanse Shcans is surely worth it but may be hard for an overnight stay. Kinderdijk is also renowned for its high density of working wind mills and is not that far from Amsterdam.
In Amsterdam, the museumplein is quite nice and there are some nice places around the Centraal Station, the old port and the Dam\Koningljik paleis. The van Gogh and Rijks museums are really nice to visit, but they won't allow pictures being taken inside if I recall correctly. Also avoid taking pictures in the Redlight district as there are a few people around there that do not really feel like ending up on your Facebook page... It is notorious that the canals in the Redlight are full of cameras. Hop-in canal rides are nice, but they will most likely be inside bubble-glass boats and it may prove hard to get nice pics.
Finally, you'll see that light is good almost all day long during the Dutch winter. The sun never really goes high in the sky so you always get some nice light in open spaces. However, the tight streets also mean that they are not very bright either.
As far as traveling with camera gear goes, I am not one to really get worried. S**t can happen with or without cameras if you are not taking care. Be insured, relaxed and aware of your surroundings... and enjoy.