I know what you mean about having a hard time picturing things. I'm very visual. I really need that picture in my mind to know what I'm doing. From what I have read, the best look comes from drifts or grouping of one particular plant. In other words picture the way the plant would naturally spread into an area. I think the word drift refers to the shape of the area that is planted like snow or sand drifts in irregular shapes. I have seen borders like you suggest, but I don't think they look as good as if you use the drift idea.

Your plan wouldn't provide as much shelter as if the arborvitae were planted in clumps, as clumps provide better thermal cover than single plants, especially when alternated with a deciduous shrub like viburnum. Also, I would consider using an evergreen that also provides food and shelter such as one of the many junipers or Eastern Red Cedar (Juniperus virginiana) as they provide berries that birds such as Robins and Cedar Waxwings will eagerly consumer in winter while the evergreen effect will still provide a winter roosting retreat for other birds.

BN

I know that Eastern Red Cedar is a native around here, but they get huge. I need something to go right up next to the side of the house, which is why I was thinking arborvitae. I know I can find those that grow to be more like 10-12' high and ~4' wide. Are there vaguely native junipers that would make the birds happy and not be huge?

Try Common Juniper (see link below). It is native to your area, or close to it, stays a shrub in size, and still provides juniper berries for birds. You may also consider holly for an evergreen shrub border, particularly on the east side of the house that would be shaded by mid-day. With hollies, make sure you have 1 boy to every three girls for good berry set.

Good luck!

BN

Here is a link that might be useful: common juniper info

Red cedar and juniper are the same thing--the Latin name is Juniperus virginiana. It needs full sun.

I have a west-facing wall with few windows that someone had the forethought to plant with hemlock maybe 40 or 50 years ago. So I have a solid double row of hemlocks providing almost complete privacy on that side, plus shelter and food for critters. Hemlock is the most shade-tolerant evergreen, but it is also very slow-growing.

If you can use deciduous shrubs in this area, you have lots of choices. Many native dogwoods and viburnums will do great with an eastern exposure, and they will fill in fairly quickly. You could fill in with a few evergreens.