Cavalier King Charles Spaniels are one of the BEST breeds for families with little ones. They are so loving and so tolerant and very smart and easy to train! "The Dog Breed Bible" says "Cavaliers are sweet, gentle, playful, willing to please, affectionate, and quiet! You could look into getting an older "rescue" Cavalier King Charles but if your children are young, you should start with about a 7-8 week old puppy. ALWAYS VISIT THE BREEDERS TO MAKE SURE IT IS NOT A PUPPY MILL AND ASK TO SEE WHERE THE DOGS ARE KEPT (if they don't want to do that, it's a big warning sign!).
The breeder should give you at least a year health guarantee. Be weary of those who offer a 24 hr. or so health guarantee. Try to find a breeder that just strictly breeds King Charles and not a bunch of toy breeds or worse yet, a bunch of "designer breeds". They should be very helpful and knowledgeable about the breed. Like I said, always go get the puppy IN PERSON at THEIR HOME. Spend at least an hour asking questions and seeing what pup she or he may think would be best for your brood!
They are not easily startled by sudden movement, and do not mind being grabbed. On the other hand it's important to keep a leash on your dog in public because some children may be afraid of dogs (yes, even these guys) and will react badly to being licked or jumped on.