Thanks for the responses. Yaardvark, thanks for the comments. Did you mean by extend the patio, by creating more concrete block patio? I'm not a fan of the look of this and was thinking of either decking over top or demo'ing it. Good points on the left side of the fence. that's really only the area that gets good sunlight. I've grown stuff there before. Same with the right side of the fence.. basically anywhere where the house isn't creating shade. NHBabs, thanks for the comments. What other goals do you have? We want a functional space where we can enjoy with family, i.e. outside dinners, hanging out with friends, etc. Our boys are outside kids and run around with other kids on the block in the green space behind our house, they rarely enter our backyard. Outdoor cooking? Yes definetly. I was thinking of a bbq area with an overhang pergola for a bbq spot in that "nook" area beside the staircase. Privacy? Not really a concern, the tall cedars give us plenty of space. Of what is there, do you like it? (I am looking at that row of Arborvitae and wondering if they need to be there.) The cedars are nice and give us privacy, which we like. Are there views you want to enhance or block? No, there are no views. behind our backyard is a greenspace and walkway which gets quite a bit of traffic on weekends.. we want to keep people out of sight. What is your budget? (I am not asking for specifics, but you need to consider it.) $5-8K Does it make more sense to have the patio demo'ed or to put on a rail for safety and then do patio of similar blocks a step down? Yes, this was my thinking. I was actually thinking that lower area might make a nice small hot tub area. Would putting in a wood deck on piers over the storm drain and its steep grade give you more workable space? yes, this was another though of mine, the only problem is you would have to put up some sort of shade/blind as you will be quite high now looking over the neighbours yard. What general plant types/shapes, placed where, would give you what you want to soften the space, add ornament, and meet other functions (cutting garden, shade, privacy, etc)? All great points and worth thinking about. I need help with the design. This is where I lack skill and decision making. Floral_uk - my dad and I solarized the lawn last summer/fall, we put tarps over the whole lawn to kill everything off. Moss stayed though and as such it's very squishy and ya drainage appears to be an issue. The builders are garbage in my area and they basically just threw down a small amount of soil and sod over the back yard.. if I was keeping grass I'd consider redoing the drainage.

I was thinking hostas also. We have one planted by the previous owners in a tiny little patch of dirt that got weedwhacked once by accident and yet the next year came back gangbusters anyway. For safety I’d see about painting a strip along the edge of the concrete, though, to highlight that it is a step. Something simple like a narrow band of white or some other light color will do the trick, plus maybe tuck some lights in with the planting to help make the edge show up when it’s dark. (Like actually pointed at the side of the concrete pad or washing it - you want to create a visual difference between the concrete pad and the planing bed so people don’t think the pad continues and fall off.) You could do that with some small spotlight type lights on the fence, too, pointed at the edge.

Ideas/considerations for when you talk with a real landscape architect: - how much gardening and of what kind are you/your wife wanting to do? Flowers, veggies, easy-care shrubbery? - how much lawn do you want to manicure and mow every week (personally I'd minimize the lawn, maximize your lovely woodland and natural meadow space). - if you can get electric to the hangar, do it. - cohesive yard: maybe a three-rail wood fence (backed with wire to contain pets) around the whole perimeter. If you do a fence, remember to include gates at strategic places wide enough for mowers, carts, etc. - any DIY skills or inclination? - dogs: You look like you're out in the country a bit, and big barky dogs are not a bad thing to have near the house. I like having a doggie door to give dogs access any time they want to their own dog run (an area maybe 6' wide by 15' long, fenced with 5 or 6' tall chain link). That way they can go in and out by themselves, and be contained in an area that you know is safe and escape-proof (deer, rabbits, and squirrels are such fun to chase). A normal fence can surround any other area you want them to play in while you're able to keep a closer eye on them. Not sure any of this was of help, but good luck anyhow.

Two comments stand out. First, "it doesn't rain much here"; second, "I assume this slope has survived ok for the past 70 years". The rain issue - if you are in a region which is on the dry side now, a heavy rainstorm could cause a flash flooding issue. Second, as with infrastructure which is 70 years old, if maintenance is not performed - or an inspection by a civil engineer at the least - you could have a slope failure. It is hard to know what type of weight is above the wall or if structural changes have taken place at the properties above you which could cascade down to you. I would have a professional (engineer, not landscaper) assess the site to point out possible issues. If you rebuild any part of it, I would incorporate some type of drain/ditch/trench along the bottom of the wall to help divert possible runoff from running into your house. If you do rebuild, at least a couple of stepped terraces would seem prudent. Then, I would replant with something native that would be beneficial for the slope stability. Not knowing your region, I couldn't begin to make a suggestion. But deep roots, ability to withstand drought, lower in height, and spreading should be qualities to look for in a shrub. You can always intersperse clumps of colorful perennials for pollinators amongst low growing greenery.