Leiden or Delf (mid-Sep)

We stayed in Leiden last April and very much enjoyed it. We day tripped to Delft, which we also enjoyed, you probably can’t go wrong with either choice, there’s many photo opportunities and plenty history. Leiden is very easily connected by train to Amsterdam for when you embark your river cruise.

In Leiden we stayed at Boutique Hotel d’Oude Morsch. I would stay there again just for the breakfasts!

We spent a week in the university town of Leiden(both John Quincy Adams and Einstein attended the university.) We rented an AirBnB. The university gives a lot of energy to Leiden.it is very charming with many canals.
It has the Pilgrim History as they lived in Leiden for ten years after escaping from England; finally after ten years in Leiden sailed to the New World.
Both The Hague and Delft( note spelling) are quite near to Leiden. Rotterdam is a little farther but very worthwhile as you can take a river boat to visit Kinderdijk with its 19 historic windmills.
Have dinner at In Den Doofpot. For brewpubs, they will be Belgian. We ate at Olivier. I recommend both places we ate listed here.
We enjoyed visiting Delft but if we return, we will stay in Leiden again

We spent a few days in Leiden last October ( and the same 6 years ago as well.) Here's a trip report from our recent visit:

https://community.ricksteves.com/travel-forum/trip-reports/one-more-mini-trip-report-four-days-in-leiden-and-one-night-at-a-schiphol-hotel

And a review of our hotel: https://community.ricksteves.com/travel-forum/netherlands-reviews/city-hotel-nieuw-minerva-leiden-the-netherlands

I really enjoyed Leiden, which is a beautiful university town. It is the home of Leiden University, which is one of the oldest universities in the country, and is quite lovely with charming cobblestone streets, 17th century gabled houses. It has many historic buildings but does not have the "touristy" feel of many other places. It's a much more livable feel. The city has many picturesque canals and waterways, which are lovely to walk along and there are boat tours you can take. And there are lots of parks, gardens, and green spaces in Leiden.

There are several museums, including the Rijksmuseum van Oudheden (National Museum of Antiquities), which has an wonderful collection of Egyptian artifacts. There is the Museum De Lakenhal (Municipal Museum), and the Naturalis Biodiversity Center. The Hortus Botanicus (botanical garden), which was established in 1590, was the site of the planting of Holland’s first tulip bulbs in 1593. Rembrandt was born in Leiden, and Albert Einstein taught at Leiden University. St. Pieterskerk is quite historic and worth seeing, even if you just check out the outside of it. Rembrandt's parents were married and buried there.

In terms of transportation, Leiden has very easy access by train to other cities in the Netherlands. I really cannot recommend Leiden enough.

+1 for the previous replies. If you feel you have the time and energy, Delft is a trivial unreserved train excursion from Leiden. I think the photo opportunities in Delft are unique, but it is MUCH smaller than Leiden, which is pretty enough. There is much more to do in Leiden, although Den Haag is right beside Delft, and could make a busy three days there; for example, The Girl With A Pearl Earring, if it's not out on loan.

From Leiden to Delft ore vice versa is just 21 minutes with the train. Think too Leiden is the better place and with the museums there is more to do. Besides the already mentioned museums is Museum Boerhave very interesting about the history of science and medicine and there is also a windmill museum you can visit. https://rijksmuseumboerhaave.nl/english/

Not only Einstein but also Oppenheimer taught (in Dutch!) at Leiden University. Einstein was friends with Hendrik Lorentz who was professor of the faculty of theoritical physics there and one of his inspirators.

Last year, we spent several days in May in Delft and enjoyed it a lot. This year we will be staying in Leiden for a few days.

In Delft, we did a lot of bike riding in the surrounding countryside including one ride down to Rotterdam for the RS city walk. It really was a blast. We really enjoyed some of the places we ate in Delft, but mainly because we sat outside, in the sun, drinking Dutch and Belgian beers, and watching the world go by. That seems to make most meals tasty :).
A couple neat spots just outside Delft on our rides were a small brewpub - De Koperen Kat - and another little place on the way out - Huszar - which had seating on a barge in the river. We found many places across the Netherlands had restaurants with good views of or on the canals, and we often stopped for food, a snack, or a beer. In Delft, we also liked a very "simple" rijsttafel at De Parel van Flores near the center of town.