All females would produce less aggression, the males will still get stupid and aggressive towards your other poultry even if they do not have their own Hens to focus on/be protective of. So IMO your best bet is to just add a few Guinea HENS into your existing flock of chickens. It's always a good idea (no matter which sex of Guineas you are adding to your coop) to make sure you have plenty of coop and roosting space plus extra feeders and waterers, just to avoid any potential aggression issues.
Unless you have a large coop and you are going to get a good sized flock of male and female Guineas that can focus on each other, IMO you are better off just building the Guineas their own coop and run, and spare your chickens the aggression issues that come hand in hand when integrating both types of poultry, since they have not been raised together since day one.
