Why would you want to get a dog? Because in exchange for getting a dog, they are all going to pick up some slack for you. Your nine-year-old is old enough to take all the childrens' dirty laundry and put it in the laundry room for you. And he's old enough to put clean childrens' laundry away properly. He's old enough to be the one to feed the dog. You will have to tell him to do all of these things. He can also let the dog out into the backyard and let him back in. You will have to tell him to do this, every time, but by the time he is 12 or 13 he will do it without asking, but only if you take it for granted that he must do this, like getting dressed in the morning. He can also clear the table. He will also have to make his bed every morning and put his toys away. You will probably have to show him how to clean his room, one corner at a time. But he is going to have to do it to show he's responsible enough for a dog.
The six year old can put the clean towels in the linen closet if they're kept low enough. She can also set the dinner table. She can put her toys in a toy box and pick up her room and make her bed.
The three year old can use a feather duster and pick up the toys in the family room and put them in a toy box.
Your husband is going to empty the trash every day. He is going to be the one to clean the toilet in the master bathroom. If he wants a dog, he is going to do these extra chores. Period. Or you pick other chores you think he can do that you hate. One or two chores.
This is what they're going to have to do for six weeks to earn a dog (by that time it will be a habit). Not that they stop doing it after six weeks. It's that you privately are going to tell yourself that they have to do these chores for six weeks without arguing before you will consider a dog. Tell them they have to earn a dog by showing increased responsibility at home before you get the dog, not after.
If they refuse to pick up the slack for you, you can say, "Look, the dog adds work. You guys won't even do your own chores."
If you have a fenced-in yard, half the work is already done. Then you need a crate. For the first couple of weeks, you will be supervising a puppy (gate the kitchen, in case of "accidents"), and putting the puppy outside every half hour. When she pees or poops outside, praise her and give her a treat. Give her attention.
As for breed, that depends on the size of your yard. We got two dogs because border collies can be high-strung and they make it their job to keep each other in line. And if the cat slips out they shepherd her back in. But I wouldn't recommend a border collie for everyone. Just don't get a beagle. They're small but they're definitely outdoor dogs for folks who are always outside.
Some of your smaller dogs are pretty stubborn, like Dachshunds.
Newfoundlands are great dogs, although they drool and shed.
You are right, though, the kids are too young to be relied upon to take care of an animal. That's simply not realistic, unless you live on a working farm.
Who walks the dogs? Me. About 15-20 miles a week (except THIS week! Brrr!). It does wonders for their behavior. Even though they poop in the back yard, they still need a walk. It also does wonders for the waistline.
It really adds to the joy in the house to have pets.