Almost any dog introduced into a home w/o children will be, at least, somewhat jealous when, say 5yrs down the road, one shows up in his home.
Do your homework, get a dog that fits your lifestyle, NOT one that you'll have to adjust your lifestyle for. You have to consider the dogs needs for exercise, grooming, attention, and possible medical problems. Sometimes that means considering a somewhat homely breed(yes there are homely dogs).
Labs are cool, they like water. My friends lab always liked to roll in something dead(YUK). I'm not a fan of German Shepherds or Pit Bulls. Too much inbreeding and improper raising/training associated with both of them. It's hard to find a dog that is bred for the betterment of the breed as opposed to one that's been bred for making money.
There were several breeds that I had on the list, Bernese Mountain Dog, Kuvasz, Great Pyreness, and the Akita. We chose an Akita, each dog had it's ups and downs(some had more downs than ups). After weighing the pros and cons, we then began a search for a reputable breeder. I bought a book before we contacted a breeder, they give you and idea of what to expect with w/e breed. We took our (at the time) 4yr old to meet the puppies, to see if the puppy would bond with the youngest one of the pack. After about 5mins the puppy was following her around their yard. My daughter picked up a stick and started to break it as she walked, so the puppy did the same. It's been over 3yrs, and our Akita is the most loyal, protective, and obedient dog I've seen. Alot of times she knows what she's supposed to do w/o being commanded.
Here are some don'ts. DO NOT buy from a 'pet store' in the mall, not ever. BE wary of ads in the newspaper, especially ones for cheap. Don't buy a dog because it looks cool, those looks only go so far, if it has an irritating personality. Since you are considering children during the lifespan of said dog, I don't recommend going to the pound and getting a 'used' dog. Like used cars, they are there for a reason, a reason that you may not find out until it's too late. Don't buy a puppy if the breeder won't let you meet the parents.
That being said, a lab is probably a safe choice, IF the dog fits your lifestyle. Do your research and find a good breeder. Go to Petsmart or a local dog park and talk to the owners about their experiences with their dogs.