I visited the Desert Botanical Garden last week with my mom and it is totally amazing! I have been to other botanical gardens but this one is so unique because it is all cacti!! I have never seen anything like it in my life. There are probably hundreds of different types of cacti here, plus several birds and other wildlife. I saw a roadrunner, a rabbit, and a thing that looked similar to a chipmunk/squirrel.
The admission is good for all day and there are several different trails that you can take. We took the main trail as it was the middle of the day and it was 114 degrees outside. The great thing is, they have a few buildings on the trail so that you can stop to cool off. They also have water stations spaced throughout the park so that you do not become dehydrated. The store is quite good with a wide variety of different souvenirs available. There is also a nice restaurant on site. We didn't dine there, but it looked nice.
I would definitely highly recommend visiting the botanical gardens to others looking for a great experience in Phoenix. I saw that they offer lots of evening programs so if I'm ever in Phoenix again, I'll definitely go back in the evening!