Spreewald Accomodations

I would suggest staying in Lubbenau, went to the Spreewald only once. That was in 1999 as a day trip from Berlin.

It has been several years for me too. I thought it would be nice to stay in an old original place. Bad idea, old rundown, big spiders, breakfast in another place and old East style etc. We stayed near Lübbenau. The area is active around Mittagessen, with bus loads of tourists, then goes very quiet in the late afternoon. Restaurants close early. Some boats on the canals for tours at night. Walking thru the woods is like seeing the same 100 meters for kilometers. We did not stay here, but it looked nice. it is near the Freilandmuseum Lehde too. I think the minimum stay is two nights though. Around this area is probably what you are looking for.
https://www.bludnik.de/

I visited both Lübben and then Lübbenau in 1999. Lübbenau is by far more interesting, saw historical plaques dating back to 1813 during the " War of Liberation" (der Befreiungskrieg) against Napoleon commemorating what took place in that greater Berlin area.