A pergola will obstruct light into the structure. What is the structure used for? How do you plan to use the deck for? Eating? Sitting? etc? Plan the activities and the furniture you'll need and draw up a floor plan. Floor plans are important outside & inside. The steps to the deck from the lawn are a little too abrupt. Needs a transition. Consider adding cement pavers to the grass, not as an extra patio but for a nicer transition design.

You have done a beautiful job of tucking plants into the crevices of your retaining walls. Your house trim color is perfect -- just slightly lighter in hue than the retaining wall blocks. First I would paint the big, flat gray wall slightly lighter than the blocks and slightly darker than the house trim. The concrete walk and stairs I would stain a mottled blend of the blocks and the house trim colors. Next would be to paint the railing black or the house body color. Now, think of the following as creating a light, airy trellise structure from the walk-level face of the (currently gray) wall to about 7' above the top of the wall (using 6x6" posts attached to the wall) with a corresponding line of posts sunk into the terrace level 2' in from the outside edge of the wall-attached posts. The inside posts would be about 6-8" higher than the outside posts. Put 4x4" wood to attach the outside line of posts to each other and do the same with the inside line of posts. Run wood pieces at the top of the two lines of posts from the inside line to the outside line at about a 45 degree angle. They would be cantilevered up at the terrace level. Across the top of the angled pieces create your top trellise boards which run parallel to the two lines of posts. OK. There you have your basic structure. You might want to extend the structure around to follow the street side of the terrace. You could then follow the suggestion of reom10 above about creating a bench-planter on the terrace side. Your spacing of the boards parallel to the gray wall and attached to the outside posts would determine how private you wanted your terrace to be. You might want to soften the terrace "floor" by using something irregular like flagstone with groundcover plantings between the stones. From the latticework on top of your structure you could hang seasonal flower baskets. Plant vines to go up the trellis and spill down the wall. How about planting a row of tall, narrow shrubs along the neighbor's fence above your terrace to help add to your privacy and make your yard feel less 'structured'? Or, how about patio table/s with umbrellas to block your neighbor's view? Anyway, you have a fun project ahead of you.

I won't bother with lattice, barrels are partially obscured from the street by fencing and if I put it up I would have to work around the lattice in order to turn the valves for water. If I can just make better use of collected water I'll be happy. We are at the end of our growing season so I should be cleaning up the garden and putting it to bed for the winter, just can't seem to get motivated. We had our first frost last week. Usually, our average early frost date is 1 November. I got almost no produce from garden this year, but there is always next year. Chookchook2 I've seen some of those decorative metal panels and they are gorgeous, sure hope your budget will allow you to get some before too long. Most of our state has been on fire for a good part of the summer. The closest is across the river from us and they have been battling it for almost a month. Some friends have had to evacuate repeatedly. We've only been concerned once, a small grass fire on our side of the river on a day we had wind gusts up to 65mph. Fortunately, it was put out quickly. Australia and New Zealand have both sent firefighters to help with the blazes. I can't begin to tell you how appreciative we are. The closest fire was fought for almost a week by local volunteers only as there were no other resources available. They were all on other fires. The Army National Guard (reserve troops) were called out to help with support duties and for the first time ever the federal Department of Natural Resources (DNR) asked for civilian volunteers to help with non firefighting tasks, cutting fire breaks, moving supplies etc.

I agree with havingfun, thicken the supports and have something growing trailing up them. I didn't even notice there was a pergola until the close up. Right now it blends in too well with the house color, consider painting it a different color. I don't know your usda zone but classic climbers for a pergola include clematis, wisteria, grape https://www.houzz.com/photos/santa-ynez-valley-mediterranean-porch-santa-barbara-phvw-vp~2485412 or go for a modern look You can also hang string lights, planters or something from the beams. Also agree lighten the front door.