Hi Edward,
I do love Disney's Animal Kingdom Villas - Kidani Village. It is a beautiful resort, with so much to do. Be sure to consult the schedule that you are given upon check in for all of the great activities happening at the resort during your stay, including campfires a daily activities at Community Hall.
Given the dates of your stay, I believe that throughout your vacation the crowds are going to vary from day to day. My guess is that early in your vacation, the crowds will not be too heavy. This is because you are going at a time of year when children in many school districts are just beginning to head back to school, and your arrival date is Tuesday so it's mid-week and less likely to be crowded. However, as you get toward the end of your trip and heading into the weekend, it will be Labor Day weekend, so you can expect the crowds to be a bit higher. I like to consult touringplans.com for predictions of crowds at Walt Disney World. The crowd calendars on that site predict what crowds will be overall at Walt Disney World, as well as in each park.
I absolutely recommend making the water parks a part of your vacation! They are so much fun, and my daughter asks to go to one every time we visit Walt Disney World. It will be warm at the time of year you are going, so a day at a water park will be refreshing. Whether you chose to visit
Disney's Typhoon Lagoon or
Disney's Blizzard Beach, it will be a nice way to cool off for a day.
I hope this information helps, Edward. Please do not hesitate to ask if you have any further questions!