I'd post over in the Porches & Decks forum on THS! Here is a link that might be useful: Porches & Decks

Rick, what's your planting zone? How much sun would the trees get if they were planted next to the fence (i.e. What direction is the fence on)? How much space are you willing to allow for the hedge? You mention the houses being close, so just wondering how much room you have for trees. If you have the space for Leyland's, I would highly recommend you consider Thuja 'Green Giant' instead. They are much healthier, fuller, and extremely fast growing like Leyland. I ignored the advice on these forums and planted 5 leylands a couple years ago.. at the same time I also planted 2 green giants. Both have grown very fast, but the leyland's look terrible. I will be replacing with more gg's this fall. If the fence is blocking an eye sore like messy neighbors, it will certainly be a selling feature for the house in the future... probably won't add a ton of value, but likely a nice selling point. As far as noise... don't expect even the densest hedge to do much there, it won't. For that you might consider adding a nice water feature to your yard. Sound of running water is nice and will really help drown out the neighbors. Good Luck!

It actually was not complete in this picture. The fence is in the mountains in Los Gatos Ca.. Lots of wildlife and a lot of deer. See how the posts are extended in the picture, 2' above the top rails (2x4s) we installed black vinyl barb-less wire every foot to the top which is 8'. I do not have a picture of when we finished that part of this fence as I just looked. Here is some information that is interesting: we could have run the wire 3' above the solid Howard wire fence. A deer will not jump through an opening. Ill attach a pic of a true deer fence. 8' is the magic number. I build a lot of vineyard fences and deer will get over a 7' fence if they see something that looks tasty. A true deer fence galvanized is what is called graduated wire. The holes on the bottom are 2x4"s and as it gets higher the hole size graduates to 3"x 3" the 5"x 5"s. And you dig down about 6"s and bury the wire in the ground. A trick I picked up in the hole we cut the wire on the bottom of the fence every few inches and pull it away from the fence in the hole. It keeps rabbits and other critters from digging. Once they hit the sharp side of the wire they give up fast. It really does work. The bottom pic is another fence with barb-less wire on top. Dogs will not jump that fence with the barb-less wire and a squirrel, well as you know a squirrel can get into about anything it wants. Their squirrely..lol. When you see an animal climbing across a telephone wire....they go where they want. There is another method for keeping squirrels out but its not a fence. This is a 6' welded wire fence to keep dogs and small animals in or out. But deer will jump it with ease. The fence below has barb-less wire as the first fence had. Click on the picture to see the barb-less wire. By extending the tops 2" you can turn a 6' horse fence into an 8' deer fence. Using welded wire as shown in another post on top. As for snakes the only thing I have find that works in the 30 years is snake wire. Thanks for pointing that out in the pic. Have a wonderful life!

Fence costs are catch-as-catch-can. If the landlord neighbor didn't want to pay for the fence when it was built, nothing you can do about that. You either pay for the fence and make it yours, or don't put it up. If you want a fence that bad, you pay for it. It's certainly not fair to demand payment later when someone else moves in. It's very common to set back fences 6" in my city. I don't know if it's a requirement. I do know it's common for adverse possession to only apply if someone is squatting without permission. IF the fence regulations already require a setback, I can't imagine an adverse possession case getting any traction based on the fact that the fence was built to code. Even if there's no setback requirement, you may still be protected if you specifically allow someone to use YOUR land, as in giving a neighbor permission to use the 6" strip. Or, if you specifically prohibit it. "Squatter's rights" to land usually apply when the neighbor used it and the owner knew about it and did nothing. Our neighbors accidentally put a block wall raised bed a few inches past the line. They moved. The new neighbors brought it to my attention and I said they didn't have to remove the entire wall on my account (it's only 4 feet long anyway). I gave them permission to encroach on my property with their wall. It's still my property and will remain so. Of course, it should really be in writing because if it ever goes to court, there's no documentation, but in my case it's a de minimus condition, and we get along fine with the neighbors.