"I don't know what to mix in this case - any thoughts?" Sorry, but I can't suggest appropriate plants as I've spent little time in your part of the world, and none in northern LA. I've spent several weeks based in NOLA for work, that's it. I just wanted you to be aware that you won't get an even dense hedge of one species with the variability of light levels. I have a more casual style (I live on an old farm) than what appeals to you, so instead of hedges of one species, for the most part I have mixed shrubs, with multiples of each species, mixed along the length of the shrub border. Only in one spot do I have a row of all the same species, and that is in full sun from all sides so that the plants grow at a fairly similar rate. My usual suggestion in this type of situation is that you visit neighborhoods where the gardening appeals to you to get ideas, or if there are garden centers or nurseries with demonstration gardens or if there is an arboretum or public park or botanic garden where you can look at the various types of plantings that they have. To get an ID on a particular plant (if it's not in a situation where it is labeled) take photos of leaves, blooms or fruit, branches and the whole plant, and post on the Name that Plant forum. Or visit the public library and look for books that have landscaping photos for your general area or look at photos here on Houzz that are from your part of the US and see what inspires you. You want to keep in mind that you don't want a huge amount of pruning (so check growth rates once you know names) and that you don't want excessive amounts of shedding of blooms, leaves, seeds, and branches, so something that blooms all summer might be messier than you want to groom. Here's a photo from Derviss Design/Michelle Derviss - she sometimes participates in these forums. Though her area is different (CA coast) it shows a similarly shaped yard with varying light levels around the perimeter and so a mix of plants. She hasn't tried to totally cover up the fence, but there is a mix of different textures and foliage color and varied plant heights. If you look at the closer photos of the pots (go to link below) they also rely largely on foliage rather than flowers. I am not suggesting that you try to emulate this, just that this is one way to approach your problem. http://www.houzz.com/projects/312471/napa-valley-outdoor-living

some ideas using Red Dogwood, Black Dragon Cryptomeria, Southern Charm Dwarf Magnolia, Van H Spirea & Canyon Creek Abelia:

Azaleas and Rhodos should do well as an understory by your trees. Swamp Azalea is native to much of the Eastern US and does well in wet areas.

Since no planting can be figured out until the hardscape is planned, you should limit your request for help to hardscape to start with. It's going to be hard to help with hardscape until you can make the site and your expectations better understood. Will there be walks that link various doors? These should be made obvious on the plan. Would the larger patio be adjacent to the deck? Is this the front yard or the back? Do guests enter the property through this yard? Is that the permanent location of the hot tub? You didn't mention a fence around the carport. Is that a passing thought or something you're committing to? It's important to stay at a single position with the camera while capturing a view. I would suggest you show us the yard from this view (see plan) providing a full 180* of slightly overlapping pictures. Because the area is at a lower level, it would be best if you found something 2 or 3 feet high to stand on for the pictures, and hold the camera in the vertical format. If possible, set the pictures to a size or two up from what you're showing above, as those are small. The above pictures might have loaded sideways if you're uploading them from a phone. Try submitting new pictures via computer.