Check out the Tucson Botanical Gardens for desert landscaping. Not sure where you can find water falls or lakes in the Tucson desert that's accessible for elders other than possibly Agua Caliente Park. Good luck and congratulations. If you need a videographer, we'd love to talk to you.
You might try Lowes Ventana or one of the other resorts in town. You are going to have a very hard time finding lots of vegetation and water here in Tucson. You have remember we live in the desert and they are very strict on how water is used here. Agua Caliente is probably as lush as it gets in Tucson. The Botanical gardens are very nice to and they are priced very resonably.It is good you have some time because the gardens book very quickly.