A lot of factors contribute to whether or not you have a good flight, but often it comes down to the people. If you're seated next to someone you like, you'll probably enjoy your flight. If you're sitting next to someone noisy, you can bet it won't be too much fun. This isn't an easy problem to solve, but here's the best way to go about it.
Silence the Noisy People
Noisy people are one of the toughest problems on a plane. People have a right to talk at a reasonable volume, and "reasonable" is often subjectively defined. Some people are often not in complete control of the noises they're making. For example, if you're sitting beside a man who's asleep and snoring the entire time, he may not be entirely aware of what he's doing to your sanity. Whatever the case may be, the person making the noise may not agree that they're being a problem. As a result, you have to approach the situation delicately but firmly.
Before you do anything, it's best to be on friendly terms with the people in your row. This is most easily done by an introduction and a short conversation before the flight takes off. Also, if you have the opportunity to do them a favour — such as help with their luggage or answer a question about the flight — they'll be more inclined to do you the favour of shutting up if they're being noisy. This is important because we're talking about two very distinct first impressions. If you do someone a favour or just come across as nice early on, you're a nice person asking for something. If the first thing out of your mouth to the person next to you is "could you please quieten down a little?", you sound a little more like a whiney jerk (or a cartoon librarian).
Even if you don't get started off on the right foot, if you want to ask someone to be quiet you want to find a good balance between kindness and firmness. For the most part, this is going to be in your delivery, as practically anything you say will come across as nice — or the opposite of nice — if you say it that way. So long as your delivery is sound all you really need to do is give context to your request. Here's an example:
I didn't get much sleep last night. Would you mind talking softly so I can try and sleep a little on the plane?
Or maybe you have work to do:
I have a lot of work to finish on this flight and I have a hard time concentrating when people are talking. I'm not asking you to stop, but if you could be a little more quiet I'd really appreciate it.
There are no magic words, but you're more likely to make progress if the person feels like they're doing you a favour. People do like to help other people, and if you're sincere, they'll be more likely to help you. Nobody likes being asked to shut up, but you can negate that feeling a little by asking for a favour at the same time.
Silence the Noisy Children
If aeroplanes had a family section we might not have such a problem, but they don't (mostly). Before you get too angry about a crying baby on a plane, it's important to remember that parents only have so much control over their children. They don't have a magic wand to silence the screams. It's likely that we all caused problems on a flight when we were children. To some extent, the next generation is paying you back for it.
All of that said, there's a significant difference between a baby that cries during altitude changes and a child who is obnoxious throughout the entire flight. Some kids kick and scream despite being old enough to know better, and some parents don't do much about it. This is where you should feel it's OK to step in.
The best practices in this case aren't much different from asking a noisy person to be quiet, except you're directing your request at the parent of the little noisemaker and not the problem child. I asked parents on Faceboook how they'd handle this situation, as I don't have children of my own, and sympathy turned out to be a key factor. Harper, one parent of small children, explained the situation from her perspective:
Most parents know that their kids are being a nuisance and feel really bad about it, but are also afraid to look bad and/or add to the ruckus by yelling at the kid to behave. It's a catch 22 that makes it so they wind up not doing anything until they get home, even though the kid is making everyone, esp. the parent, miserable. Don't really know how I would like to be approached about it by the people around me, but having small kids has helped me to understand how bad the parent already feels about the whole situation.
Jon, another parent, suggests a good way to be sympathetic:
Try saying this directly to the parents: "Wow, you must be really frustrated by this behavior?" and I guarantee that most parents will feel relieved that they are not getting attacked for not being able to control their child. They will then open up to you and I bet will work with you to get the child to realise they are out of line. Fact is (and there is a great body of evidence that proves this), is that children between the ages of 3 and 7 can not control themselves and the flight is a challenge for them. Many times when my daughter behaves this way it's because of other reasons like hunger, fatigue or needing the kind of attention or activity that just would not be good on a plane, (especially if you are sitting next to them). They have no concept of what's appropriate at certain times.
Ultimately, it's important to remember there is no perfect solution. Be kind, try to work with the parent of the noisy child, and if they're cooperative you'll at least avoid feeling angry at them over something they may not be able to control.
A Flight Attendant's Recommendation
When you can handle a noise problem yourself, that's great. Sometimes you will end up in a situation you can't resolve yourself. Fortunately, you have flight attendants, and I spoke with one to get a more official perspective on how to handle these sorts of noisy situations. Here's his advice:
If all else fails, yes, it would be time to summon the flight crew. The crew should decide if the situation is unacceptable. A flight attendant should be involved if there is an unsafe situation or if the problem would create an unacceptable situation for other passengers. A passenger might have the option to be moved, but there first needs to be an empty seat for the passenger to move to. If not, then the best-case scenario would be a trade...and perhaps you'll find no other passengers willing to trade. I suppose it might be ideal to find a deaf passenger to trade with.
You want to use your best judgment before summoning a member of the flight crew and take measures to resolve the situation yourself. If anything becomes hostile, it's time to involve a flight attendant. In most cases, however, this won't happen. You might anger someone by asking them to quiet down, but on few occasions will that anger ever rise beyond mild annoyance. That said, a passenger in front of me once yelled at me because my backpack was under his seat — you know, where it's supposed to go — and a flight attendant had to get involved to calm him down. Being the reasonable person in this situation, I received the sympathy of the flight crew and they helped me much more than they helped him. That is to say, if you need to involve a professional, make sure you're not the crazy one.