Desert Botanical Garden is a great place to go alone, with a significant other, or family/friends. The entrance fee for adults is $25 and there is a senior discount and a lower price for youth.
I dropped by with my family on a Friday afternoon around 4:00 pm in an attempt to avoid the heat. We moved through all the different areas of the botanical garden in about 2.5-3 hours and really enjoyed looking at the different plant varieties, sculptures, installations, and interactive set ups. It's a very beautiful garden which affords a few city and mountain views depending on which part of the garden you are in.
There are restrooms dispersed throughout the garden so you don't have to worry about using the bathroom as soon as you come in. There are also water fountains scattered throughout so you have a water source even if you forget your water bottle or something of that sort. There are also benches and chairs in various areas so you can sit down if you are tired or if you want to just sit in the shade, relax, and enjoy the view.