You left out the Anne Frank house, but I assume you will go there.. I would think the tulips may be WAY past their prime by that date. We went in April and the tulips were spectacular at that point. If you enjoy flowers and Keukenhof Garden is still open by when you go, it is amazing! Otherwise, again, if you are a flower fan, suggest Aalsmeer for the flower auction. That was fascinating to me. That goes on year round (I think). Volendam is also very close, and it a great day trip, exploring a lovely fishing village, learning about cheese, etc. It's been a long time since we were there, but Holland is a lovely country. Enjoy!!