One of the nicest spots in Thailand. Swam in about level 5. Most Thai waterfalls are not worth the effort but this one is. The whole province is fairly good to drive around. Sai Yok is a nice town and better than Kanchanaburi imo.
I have seen on google maps a car ferry that crosses a lake but havent done it. I was looking at doing that plus drove out to the border.
I've done the war stuff and I enjoyed it but it's not for everyone. There are hotsprings as well.
Definately a top 10 province in the country. I would say catch a train to Kanchanaburi for 2 nights then hire a car for 5 days is the go.