So your goal is pets. You are not worried about egg production, bug and pest control, showing, breeding, and very obviously not about meat. I don't know how big your area really is. The more crowded they are, the more likely bad things will happen.
Each chicken is an individual with its own personality. I find that the personality descriptions in general hold true if you have enough for averages to mean anything, but on an individual basis, they are not always absolutely correct. And you can seriously influence that by handling he chickens and such, especially if you raise them from babies.
In general, any of those breeds should work. It is always possible that you will get a Matilda the Hun who is off the scale. Chickens have their psychos too.
Sometimes you will get a Silkie that will dominate a mixed flock, but they are usually more laid back and can be bullied by others. They usually make great pets and usually get along in a mixed flock. I'd certainly try one if your wife likes them.
RIR and Wyandottes don't have that great a reputation in general as tremendously great in a flock. They can be aggressive toward other chickens. Many people have them as pets and keep them in a mixed flock with no problems. You already have a Wyandotte. You can see what she is like. I won't say that RIR or Wyandotte are horrible choices either as pets or for their behavior in a mixed flock, but I'd think from breed tendencies, the BR or BA are probably better choices. I assure you many, many people that have RIR or Wyandottes will disagree with me on that.
Sex links can have many different breeds as parents. They are not a breed but a cross so they do not have a "breed" tendency as far as personalities go. It is extremely common for RIR's to be the father in a sex link cross because they have the right genes for color or pattern sexing and they come from a great egg laying line. Many people on here comment on how great a pet their sex link makes. Occasionally you will see a post where a sex link is aggresive in a flock but not all that often.
To summarize, I think with handling any of these will probably make a good pet. As far as mixing in with yout mixed flock, I don't think you will have enough that the averages mean a whole lot, but the general tendencies do. If all else is equal, I'd probably shy away from a RIR or Wyandotte, but if you have your heart set on one, I see no real reason not to try one.
