Eaton Canyon offers beautiful trails, is dog-friendly, and has a waterfall you can easily hike to. I'll take you on a step-by-step guide that will show you the correct path to take. It's a moderate hike.
The hike is located near Pasadena and Altadena. It offers free parking and a nature center where you can learn more about the area. There is also a clean bathroom inside.
Before starting the hike, keep in mind that there are rocks you'll need to climb over, but it is absolutely do-able. You'll want to go earlier in the morning, because a lot of the hike is non-shaded.
Make sure to bring water and a trash bag to collect any trash from snacks you bring. Wet-wipes and napkins ensure clean hands after touching rocks. Taking any of the animals or plant life from the park is prohibited, so leave them be. If you ignore those rails and go off the trails, you can find yourself among rattlesnakes and coyotes.
When you start the hike, veer to the left and follow signs. It'll make sure you end up at the waterfall. Do not go to Coyote Canyon if you're searching for the waterfall.
Plan on 3 hours for this hike. This time encompasses parking and the hike and for anyone who needs more time. The hike is 3.5 miles roundtrip. If you have time and are up for exploring, head down the road to the LA Arboretum. There are over 200 peacocks that run free and it's another excellent walk.