Manners are a slippery slope. I agree that I see lots of kids whose behavior/attitude I wouldn't tolerate in my own son. But- you cannot be the 'manners police' mom all the time without making everyone mad.
Pick your battles- if you are in public, at the park or mall, then just grit your teeth and bear it, unless some other child's behavior is affecting your own kid. If their parent chooses not to correct them, that's frustrating, but not your responsibility, unless the kid is endangering himself or others.
Make sure to reinforce YOUR kids' good behavior often. Praise them and have a little talk in the car on the way home. Say, " I really noticed how good you were at the park today! You shared your toy and you waited your turn in line for the swings and didn't shove anyone else out of the way. That's how we behave in our family and I am very proud of you!"
Don't single other kids out as negative, but give your child the chance to compare their behavior. Kids notice a lot more than you might think!
At your own house, its a totally different matter!
Even at a very young age, kids are totally capable of understanding that there are different ways to behave for different places and situations. Some kids are just more rowdy than others, but it is TOTALLY appropriate for you to sit everyone down and say, " Ok, these are OUR house rules. In our house, we don't climb on the furniture and throw the couch cushions around. We only have our snacks and drinks in the kitchen. We use our inside voices. We say please and thank you when we want/get something."
That said- remember these are just kids and you will have to repeat your rules over and over. Also, sometimes kids need to just blow off steam. It can help if you have a family room or a playroom and you don't care if that room gets messed up. Or say " We can build a fort with the couch cushions, but only if we clean them all up and put them back when you're done."
If you don't want them running around all crazy, you must offer them alternatives- a movie to watch, a game to play, music to dance to- something that will engage them, but not make you crazy!
It's tough in the winter, but spring is almost here. As soon as you can- bundle them up and send them OUTSIDE to run off some steam!!