I came to visit in late December and it was sort of chilly. As such, other than a few groups of school kids, I had the place almost to my self. To take in the entire property and all it has to offer takes a good 3-4 hours and I am sure I still missed some stuff. While in the gardens I got to spend some time with the curator and chat about vegetable gardening in a desert and she let me peek out back as see her little compost pile, almost as long as a football field! She was excited about having just gotten a permit from the city to start growing vegetables for the cafe. The permit required that that garden be kept out of he public area but I am sure photos will be on display somewhere after it is in production.
In addition to the gardens there are several indoor areas with lots of interactive stuff for people of all ages. Areas focus on wildlife, water conservation, and lots of historical info on the area. If you have kids in tow while visiting Vegas this is a must do side trip.