Visiting Keukenhof is a must. I've heard it's better to go in April but it was still incredible in May, even though the fields weren't in full bloom. There are many cafés and shops along the way, lots of different pockets of beautiful displays in all kinds of tulips, as well as other flowers. Inside some of the places are special exhibitions, my favourite was the lily exhibition they had on. I wish you could smell what it smelt like in there, it was unforgettable!