You mentioned a Boston Terrier and in all honesty that would probably be the best choice for you thats in your list they are great with kids, they are small (not over 20lbs), they are short haired and don't require hardly any grooming if any, and they really don't smell, and they require hardly any exercise I think they cover all of your bases most terriers are not a good choice ecspecially with children but the Boston for one is not a terrier at all as other people have mentioned it is a non-sporting breed
On the other hand if you don't mind a larger dog a Labrador Retriver is a better choice for you or any other breed in the sporting dog group
German Shorthaired or Wirehaired Pointers,
Retrivers: Chsepeake Bay, Golden, Curly Coated,& Flat Coated
Setters: English, Gordon, & Irish
Spaniels: (which are smaller): American Water, Brittany, Clumber, Cocker, English Cocker, English Springer, Field, Irish Water, Sussex, & Welsh Spinger
Also Vizsla, Weimeriner, and lastly Wirehaired Pointing Griffon
All the dogs in the sporting group are a good choice they are easily trained and in general great with children but some may have a doggy smell and require a larger amount of exercise than you can provide
Before purchasing a dog though talk to local breeders and even your vet they can help
Also if you don't want a puppy talk to your breed rescues (every breed has a rescue) you can find them on the internet or contact AKC they can tell you about your local dog rescues the rescues usually have great older dogs waitng to be rescued that are house broke and predictible another good place to look is on Petfinder.com
Good luck on your search
On the other hand if you don't mind a larger dog a Labrador Retriver is a better choice for you or any other breed in the sporting dog group
German Shorthaired or Wirehaired Pointers,
Retrivers: Chsepeake Bay, Golden, Curly Coated,& Flat Coated
Setters: English, Gordon, & Irish
Spaniels: (which are smaller): American Water, Brittany, Clumber, Cocker, English Cocker, English Springer, Field, Irish Water, Sussex, & Welsh Spinger
Also Vizsla, Weimeriner, and lastly Wirehaired Pointing Griffon
All the dogs in the sporting group are a good choice they are easily trained and in general great with children but some may have a doggy smell and require a larger amount of exercise than you can provide
Before purchasing a dog though talk to local breeders and even your vet they can help
Also if you don't want a puppy talk to your breed rescues (every breed has a rescue) you can find them on the internet or contact AKC they can tell you about your local dog rescues the rescues usually have great older dogs waitng to be rescued that are house broke and predictible another good place to look is on Petfinder.com
Good luck on your search