My wife and I were at our local REI not long ago and got to talking to one of the guys that works there who does some of their hiking classes. We got to talking about some of the more manageable hikes that include waterfalls.
He showed us this book in the store and was pointing out some specific hikes that sounds perfect for my wife and I to take on with our 4 year old.
We've been to a handful of waterfalls in the mountains over the years that have ranged from hidden and remote to highly traveled and touristy. While we've already seen some of the locations, this book is also a great resource on many others we have not. Additionally, it is filled with a ton of other useful information about the hike in and out and what to expect.