There are some breeds that are very well known to be good family dogs but you always need to take their individual histories into account. Some good breeds tend to be cav/king charles spaniels, whippets, greyhounds, retrievers. Little dogs are more fragile then big dogs (think kids jumping on their back) but then a big dog can do more damage if it bites. Big dogs also cost more to keep in food and preventative medicine. Older dogs can have histories that may affect their behaviour but puppies do bite, chew and jump. Most dogs will show some tendency towards guarding but will often dissuade intruders just by their presence. If I had kids I wouldn't pick a dog with strong guarding tendencies as this tends to spill over into other things like balls, food etc.
Dach brought up some good points. If you like a particular breed do some research as many have problems you need to look for (eg. retrievers with hip/elbow problems, skin probs etc). Grooming and activity levels are also important. Breeds like greyhounds are known as runners but their required activity is no more than any other dog. Working dogs on the other hand need a lot of exercise as do many terriers. Some dogs like foxies are notorious escape artists so think about your fencing. The size of your yard is of little importance. You can have acreage and your dog will still hang around the house looking for company. They rarely exercise themselves so you need to consider more how willing you are to commit to exercising them. Check out your local dog parks as that gives them socialisation as well as a great opportunity to run around like a nutcase.
Buy from a good shelter with staff experienced in rehoming. You will get a lot better advice for your situation than if you buy from a pet shop.
Hope this helps!