Staying in Delft for 2 nights

Are you talking about Kinderdijk?

Do not miss the 19 historic windmills at Kinderdijk!
Go to Rotterdam and take a river boat to Kinderdijk.

https://community.ricksteves.com/travel-forum/trip-reports/the-netherlands-belgium-april-2024-brought-the-rain-pants-needed-the-rain-pants

My recent Trip Report includes the details of getting to Kinderdijk. It is fantastic and beautiful and peaceful.

When is this trip? I ask because the schedule of the water bus changes for the winter season. The spring schedule changes March 31, as I remember. The Rotterdam Tourist Info Center was very responsive to email questions. Enjoy!

Note that there is a city tram connecting Delft and Den Haag. It is possible to daytrip to all these places from Amsterdam if that is necessary for your full itinerary. I found downtown Rotterdam not that interesting, but others are interested in the modern architecture, water control, and even modern dance. Kinderdijk is at the edge of town, with both water and land bus service. I would not spend extra time or money to take a ferry. Opinon. (We had a car for our Kinderdijk visit. It's also accessible by national bike paths.)

We were staying in Delft this past spring on a Rick Steves tour. On our free time, we took the train to Rotterdam, tram to the port, then the watertaxi to Kinderdijk and we were enchanted with those wonderful windmills. Others on our tour chose The Hague, and seemed to enjoy it and most went to see Vermeer's, The Girl with the Pearl Earring at the Mauritshuis.
You would probably want to choose one or the other, not both on the same day. At least if you are using public transportation.

Be sure to leave plenty of time to explore Delft itself. I took a day trip to Delft from Leiden, and it easily filled up an entire day. A lot of the fun is just walking down the side streets and along the canals. Delft is very quaint.