Bump... we went to Keukenhof today. Our second visit. The first was 6-7 years ago in May and many of the flowers were past their best. We had wanted to go in the second week of April this time (everyone says that's the optimum window) but the dates didn't work, so we went today.
The majority of the tulips were not yet open, both in the garden itself and the surrounding bulb fields (which you can drive around in an electric boat starting from the garden), but there were masses of daffodils, hyacinths, and crocuses - and some tulips. One of the pavilions had a dense display of tulips in flower under cover. In a week the place will be a riot of colour.
In some ways it was nice not being overwhelmed by border after border of yellows and reds, as it enabled (forced?) us to look closer at some of the displays. We came away with a lot of beautiful pictures regardless.
Entrance was €20 (€25 if you just rock up on the day) and the bus from Amsterdam or Schiphol adds €12 return - we thought this was good value. Food and drink are not cheap but not too crazy either, and you can take drinks or a picnic in.
One nice thing is that it's run by a non-profit and there is no corporate presence, other than the names of the bulb growers, which are mostly local family businesses. Almost anywhere else the main building (Willem Alexander Pavilion, named after the king) would be called the Microsoft Cortana Exhibit or some such nonsense.