We use a few resources to assist in planning our travels.
First and foremost is VacationsToGo. Our contact provides superb service. Even strange requests such as paying US$ amounts in Canadian $ (when the exchange rate was terrible) get handled smoothly.
For trip planning within The Netherlands we use 9292OV. This site is available in English as well as Dutch. There are some fascinating tours using public transit available. They also have a travel planner for iPhone, Android, Facebook etc. Basically you indicate the to and from stations and it tells you the schedule and the cost. There is a even a QR code provided of the details to scan into your mobile!