Imho a deck with a single step down, like you are suggesting, us the way to go.I had a wooden deck and now have patio stones. I prefer and would recommend the wooden deck. If can and are OK with the height, have it made so it it is level with the patio door threshold.
The height of the door at the wooden deck location (previous house) allowed for the deck to be level with the door more so than at this house.
Especially when I wanted to stretch the deck all the way to the fence be the next door neighbor. At this point, the top of the fence dividing us was only reaching my titties and I'm only 5'6.
The location and size of your deck will depend on other things you are planning on doing with the yard. Gazeebo, pool, play set etc.
Also, I think a desk is easier to do yourself with the help of your father and a friend than interlocking.
I did my own deck at the previous house, but I had to hire someone to do landscaping at this house.
I find it an extension of the house, and therefore use it all the time.
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