I can recommend Kampong Phluk Floating Village on the lake Tonle Sap. This is possibly the easiest to reach from the city of Siem Reap: it takes less than one hour by scooter or tuktuk or coach, the latter two to be preferred if traveling with kids, all of them pretty cheap to a western audience.
A 1 or 2 USD ticket (still cheap) is required at the entrance of the protected zone and then, once you get to the dock, you can negotiate a longer or shorter tour of the village and the surrounding area and lake.
The characteristic boats, featuring the propeller attached to a long and slender shaft and powered with second hand diesel car engines are often driven by young sailors in their twenties or thirties, and several of them have their families and kids aboard, when the boat is not too crowded. In my tour, aboard the boat there was just me, the driver, his young wife and their two nicest kids, 5-6 years old the elder, only a few months old the younger. Waters are calm and the atmosphere is suitable for all ages!
Finally, I visited in December but I could claim that February is still an appropriate time for visiting. This is one attraction that one can plan the day before, to leave after lunch and come back to Siem Reap for dinner time. I have honestly no idea if it makes sense or not to visit Kampong Phluk on your way from Siem Reap to another city, either by coach or boat.
Here is a 9 minute video from some clips I shot when I visited, on Dec. 3, 2018; here instead crocodiles in a breeding farm at the edge of the town on the same day.