The Netherlands is easily reached from mainland europe and even the UK, with a choice of sea crossings followed by a short drive.
Lively Amsterdam is the main attraction, but the towns of Haarlem, Delft, Groningen, Arnhem, Maastricht, Breda, and the Hague are certainly worth a visit. For cycling tours, the Hoge Veluwe National Park is a must, and don't forget the famous bulbfields, which are best seen in Spring.
With over 16 million people inhabiting a country that would fit into the State of Maine in the USA, much of the population in the Netherlands lives and works in the Randstad region, in major cities like Amsterdam (the capital), the Hague, Rotterdam and Utrecht.