Puppies are adorable, soft, fluffy, cute little balls of energy. Every Breed. Even mixed breeds. If you get a puppy that is NOT like I described, there is something wrong with it. If you are worried your children will not be able to respond well & play nicely with an energetic puppy, DON'T get one.
If on the other hand, you were referring to the dog once it is mature, then you need to consider the personality traits & purpose of the breeds you are considering. Some breeds are naturally good with children, & have become popular as family pets. This includes the Golden Retriever, Labrador, and many other Spaniels.
Cavaliers are great dogs, and even though they are a small breed, they have "mighty dog" syndrome. I hear from many people that it is one of the only small breed that truly acts like a larger dog, and in fact they are a member of the Spaniel family & were bred to do work in the field.
Bichon frise, Coton de tulear, & any other dog with a fine, downy coat will require a LOT of attention to grooming. This means daily brushing, as well as grooming expense every 6-8 weeks. I am not as familiar with these breeds insofar as their temperament, but given the "cuteness" factor, these (as well as Cavaliers) MUST be obtained through a reputable breeder, to avoid health & temperament issues. And I'll be honest, none of them are cheap. Litters are small, and demand is great. Expect to pay over $1K for a puppy.
An alternative to getting a puppy is to contact a breed rescue. Almost every breed has a rescue organization that works to keep the breed dogs out of the shelters, & place them into good homes. Sometimes there are puppies available, many times there are young adult dogs. Most rescues also work with foster homes, so the dog you get has been home-evaluated, and it is known if the dog is good with children, cats, other dogs, etc.
Cavachons - that is a mutt. It is taking 2 dogs of different breeds, letting them create a litter, & assigning a cutesy name to it to generate interest. I'm not going to say all mutts are bad, because we know they aren't. Many of us grew up with a mutt as our first dog, & still have them. But, if you are looking to get a dog with specific attributes, and any type of health and temperament guarantee, you will NOT get into a designer breed like this.
The reason most breeds are known for X-Y-Z trait, is because they have been bred for generations, and are able to carry those traits & temperament forward in their lineage. So if you are going to get a mixed breed, don't pay through the nose for it, thinking you are getting something "special". Go to the humane society, or local shelter & adopt.
Please, think about why you want a dog. This is a commitment for the next 10-15 years. Puppies become dogs, and dogs have needs. Make sure the puppy you get will become a dog whose needs can be met by your family, and who will become a cherished member. T.