Utrecht is beautiful, but I reccommend to go to just walk and inhale the beauty of the streets, the canals. Don't just do the common activities. In Utrecht is a lovely museum: Van Speelklok tot Pierement. Also lovely to do is a long distance walk, or short, through the woods. I went to National Park Utrechtse Heuvelrug, Landgoed Bornia in Zeist, Walking area Posbank near Arnhem. Citities like Utrecht, Amersfoort, Nijmegen, Arnhem, Enschede, Maastricht and Groningen are beautiful too. I reccommend to walk through small villages as well, they're really lovely. Walking in the province Limburg is amazing as well as in Gelderland. If you want to go to the beach, go somewhere in the province Zeeland, it is more quiet there I believe and then visist there the places as Middelburg, Vlissingen en Terneuzen, but a bike ride is lovely too there. Also, visit small museums with its local history, always interesting. Tip: use Google Maps with its local businesses on it. All the best.