Starting our build after planning for years. The first step was to retaining wall the entire back yard. Luckily I have friends in the commercial concrete construction industry. We needed to drop the grade of the entire high side of the yard by 21" to create the full to level the low side. To deal with this we created planters off the back patio which will act as the sides of the three 12' wide steps that we will pour. The walls on the left side of the yard had to be 5' high to hold the banks we created in cutting down the yard. I like the look of raw concrete walls, so I sealed them with a lightly tinted sealer. The dig began a week later for our 18x36 rectangle with 6" radius corners, and full length liner over steps. I will update as we go, pretty stoked about the project!! 
Thanks for sharing your experience. Should be fun to watch.