This is not an enormous problem, however it is something that I would like to address at some point.
Our neighborhood was built in the 70s, does not have any CCRs, and is primarily middle class folk, in the late 20's to 40's age range, but not many kids running around. We bought our house 5 years ago, and have put a lot of effort into renovating the inside and making it look pretty nice from the front. Uphill Neighbors bought their house about 3 years ago. Uphill Neighbors are 30 something triplet men who own the house together. We have always been cordial, but not particularly friendly. When they cut down a huge tree near the lot line, they asked if we minded beforehand. When we tore out some huge junipers and relandscaped, I asked if they minded if I planted a few small bushes and perennials on the 4 foot strip between their driveway and our lot line. They were happy to have someone take over landscaping the area that had previously just been juniper overgrowth. So we are on fine terms. I have a veggie garden in our back yard, and I've given them kale, zucchini, peas, tomatoes and flowers from the garden in the past.
They almost always have 5-7 cars in their driveway, what with the 3 brothers, plus girlfriends and buddies staying over all the time. They also pretty regularly have gatherings. While I wouldn't call them parties (it's not as though lots more people are showing up), they get together in the back yard and play lawn games, have fires, etc. Their primary lawn game is something called "corn hole" where you throw bean bags at a sheet of plywood with holes cut in it, trying to get them through. It's noisy. Accompanying the constant thuds of bean bags hitting plywood, you also get loud, drunk-sounding "WOOOOOOHHHH!!!!s" pretty regularly. These tournaments go on for 3-7 hours usually, well into the night. If this was happening once or twice a year, I totally understand, but it is happening at least a couple times a month, sometimes mid-week, and usually lasting past midnight. Additionally, someone there invariably brings a dog that barks at ours through the fence (our dogs are not barkers, but get agitated when dogs are yapping at them) and also barks randomly throughout the evening. This makes it so we cannot let our dogs out into the yard if we are not out there supervising them, and the dogs spend most of the time they're inside being agitated due to the on and off barking. Our bedroom is also right next to the neighbor's back yard, so we are unable to go to bed (at a normal hour) with our windows open on hot summer nights, because their yelling is so loud.
The neighbors on the other side of us can hear them and have asked us if we know what the heck is going on with them, and last weekend during one of their gatherings, the neighbor behind us (kittycorner to their back yard) was giving them the stinkeye from his bedroom window.
We kind of hoped that they would default on the home, or move, but none of that has happened, and since we intend to stay in our house for the foreseeable future, I would love to come up with a way to nicely tell them to (Oo, I just used a rude phrase that the moderators won't be happy about. ) without coming off as the grumpy neighbor who hates fun (we also occasionally have barbecues, but they're always on weekends, infrequent, and much quieter), and starting a war with them. They seem reasonable, but the last thing I'm interested in is bringing out their inner crazy.