You'll definitely want to spend a day outside the city checking this place out. The wooded area surrounding the falls is serene and peaceful, but the real draw is the fact that you can walk up the falls. The limestone is "sticky" even as the water runs over it, so you can climb up and down to your heart's content. It's a real treat, and provides a nice complement to some of the more traditional tourist activities. Aim to go on a weekday, since the place gets fairly crowded on the weekends. For between a few hundred and a thousand Thai baht, you can hire a songthaew or tuk-tuk driver to take you out and back.