Here are some ideas that may work for you:

The screening plants are Bald Cypress & Hemlock (if you do not have disease problems with Hemlocks in your area). Bald Cypress is a rapid grower.

Thank you! It looks like you’re putting the trees farther out into the yard. Is this preferable to where I have the arbs? And would these grow more quickly? (Both location wise and this type of tree compared to my green giant arborvitae?) thank you again!

You would be better off buying the biggest tree(s) you can afford, rather than 4 small trees. The kind of tree that has to be delivered and planted by a skidsteer, or somesuch equipment, by professional landscaping personnel. Go to a tree nursery for advice and assistance.

Green Giants grow very quickly in most cases & they are evergreen vs Bald Cypress. Perhaps the mix of several types of trees will serve you best. River Birch is a very fast grower, but is not evergreen. That mixed with Mountain Laurel & Holly, in addition to the previously mentioned plants could be all you need in the way of privacy. The design intent would be to recreate a naturalistic setting that screens the most objectionable views without creating the "Berlin Wall" .

I love this idea, thank you!

It looks like you placed the green giants right on the property line, which also happens to be in deep shade. To get better results, you'll need to sacrifice some of your side yard and plant in a sunnier spot. That goes for pretty much anything you would plant for privacy. That side yard is also elevated, versus the gully-like area you planted in, so should fill in a bit faster.

I consider myself a good neighbor, but I would have a good laugh if my neighbor asked me to spend thousands and thousands of dollars on a fence because *they* wanted more privacy in *their* yard. It wouldn't offend me or anything, but that's a you problem. If you want to offer to buy a fence for them or split the cost, that's different.

Yeah, I kind of agree with maybe having to sacrifice some of the yard to get the trees in a more open area. And I worded that strangely--I would never ask my neighbors to pay for a fence or privacy trees for my convenience! If a conversation on that topic ever happened, it would be about us offering to pay for a fence/ trees on the edge of their yard (due to their yard sitting up about 6 feet higher than ours). Even that doesn't sit right with me so it will probably never happen... ;)

You might like to read a previous thread on evergreens in shade for privacy. Not your exact situation, but some food for thought for how more privacy might be achieved.

To get more specific you would need to draw your yard area, lot line , height difs — up to neighbors, your ( raised?) patio, house, insofar as various structures may cast shade, ditch or swale if any , orientation ( north etc) , and tree line. Not super exact to the inch, but more details of the space and where screening desired may generate more comments on suitable plant life or man- made screening or both.

Okay, well the clarification on who pays for the fence is important. I would check to see what a fence would cost first, but if my neighbor came to me and said, "I'm thinking of planting some trees on my property to get some added privacy, but it occurred to me that a fence on your side of the line might be more effective. Is that something you'd ever be interested in? We'd cover the cost, and would maintain our side of the fence going forward," I'd probably sign right up. But the downside to that is if those people ever leave, the next person can do whatever they want.

Strange neighbor requests are nothing new to me, hence the confusion. I had a neighbor complain to me that she was certain the deer eating her plants were coming from my yard, and expected me to do something about it. I told her that they were coming into my yard from someone else's yard, so she should talk to them!

Wow. Um, nope, we just like a sense of privacy and separation from our neighbors. Sheesh.