Without a photo I am having a difficult time understanding why privacy is needed at the front end of your driveway which presumably leads to the public street? One would think privacy activities take place in the back yard. That said it is your right to want it :) But eighteen inches of width and a desired height of eight feet that behaves and stays that size is a tall order- it would be my opinion that anything you do is going to require more maintenance than it is worth unless pruning is your favorite hobby. I don't think DeGroot's would be good for privacy as they are so narrow toward the top. I have three in a group and while they are one of the best looking arborvitaes I have their use is more architectural than screening. Mine have gone from a couple of feet to approximately six/seven feet in five years. How long are you willing to wait? And I have to say that the thought of pruning a plant as naturally perfect in form as a DeGroot's makes me a little ill. Again, without a photo it is difficult to say but I would plant something thick and screening down as far as was practical and then use decorative boulders in the narrowest section. Or surprise my wonderful neighbor with some plants that he could plant on his side of the fence. Maybe a neighborly discussion is in order?

Got it. So, if the exotic invasive honeysuckles are present, then yes, they will happily move in to fill any newly-created space. Again, I'm right there with you, having dealt with numerous similar situations. You're on the right track in knowing that nature abhors a vacuum. as soon as one element is removed, something is going to move in and fill that spot. So, are you at all familiar with the cut-stump, or as I prefer to call it, cut/treat method of removing and eradicating non-native invasive woody species? We've talked at length about it here and elsewhere, so some kind of search should turn something up. That's the technique you're going to need to use if you are to have any hope of beating this honeysuckle back. It is doable. I get what you're asking, that of the possibility of the conifers appearing too stiff. I happen to like conifers a great deal, under the right conditions, and my favorite woods have both broadleaf and coniferous species. One thing that can help to soften the effect is to plant in groves, the way nature usually does. So, in nature, some disturbance-fire, windstorm, etc. -would have cleared an area. Often, conifers are among those species able to colonize such sites. As such, they are often quite closely-space initially, with the stragglers dying out over time. What is left is a rather dense grove, especially true of the genus Thuja, which is what the Green giants are. I'd rather see a grouping of them than one blob here, one blob there. I'm sure you don't have any native groves of Thuja occidentalis down your way, but up here, it is a common feature of primarily low, wet woods. And everybody-and I do mean everybody-loves the effect of these groves. From any distance at all, it looks like big, oversized moss to me. In any case, that is the type of effect I'd go for with the GG's. +oM

Were this me I'd change the strategy a bit in order to get more done with the same $. You are purchasing good sized, fairly expensive plants. But much smaller plants could achieve good growth and size within a very few years. I'm in a totally different area but am from the Midwest originally and know that things can grow fast there, too. I have trees that started out as 1-gallon pots that are now in the 15' ht range in 4-5 years. I have shrubs that started at same size and grew to 5' ht. & spread in 4 years. And a Bougainvillea trained upright on a post that is 13' height x 14' spread in the same amount of time .... from cuttings. I'm sure there are plants that could do as well for you and extend your budget substantially. Also, I wish you'd do a comprehensive planting plan before you put anything else in the ground. Dealing with spots here and there, over time, especially if not taking into account the ultimate sizes, you might end up being smothered by your own plants in a maze of sorts. I'd especially be looking into some large shrubs/small trees to screen at a distance since your yard is fairly spacious. Another thing I'd consider is vines on a trellis. Where you are considering screening adjacent to a patio, it seems like a better/cheaper option to me. In some cases I've used a device which I call an extended trellis. It's a series of posts, installed at a spacing like fence posts (every 8' or 10') on which a chain is swagged from each, connecting them. The space below the top chain is filled with some method for guiding vines to grow up to the chain. It could be parallel horizontal wires every 12", stapled from post to post. Or it could be vertical cords that run straight down from chain to stakes in the ground @ 12" intervals. The infill is temporary. If a vine reaches the chain, it can grown on itself & other adjacent vines. In short order, it becomes a solid screen. The overall trellis length can be extended as far as whatever space is available. Annual vines can start things out with quick cover. A permanent perennial vine that will take over for the long term can be installed at the same time. Vines that drape, such as Clematis, are good to use ... not those with woody cantilevering, such as Wisteria. Evergreen trees offer the advantage of winter screening, but they are harder to manipulate to fit situations as they age. I wouldn't put so much weight on them since you're not likely to be spending much time on the patio and in the back yard during much of the winter. Here's a suggestion of an alternative.

Thank you for all the input. Some interesting options I hadn’t considered. I don’t think we can plant a vine on the fence (though it would be beautiful) because it is my neighbors’ fence and they have goats. So anything that grows through or on the fence will be eaten in short order. As far as groundcover/grass goes, we are not trying to grow grass there. The green on the ground you see are just weeds. We are going to clean it all up and mulch everything well once the rest of the plants are in place. We went shopping this weekend and bought cherry laurels, Japanese ligustrum, wax myrtle, cleyera, evergreen and deciduous viburnum, anise, winterberry holly, some more cryptomeria and a couple thuja gg, panicle and macrophylla hydrangea, distyllium, rhododendron, fothergilla, and some perennials and creepers for along the wall. I know it sounds like a lot for the space, but the picture only shows about half of the area we are working on. We also have a lot of other places we can plant things if we find we bought too much.