Need opinions on moving dogs in together that have never lived together...?

I just bought a house and plan on moving in within the next couple of weeks with my two small 6 year old dogs-a male American Eskimo and a female Pug. My boyfriend will most likely be moving in with me sometime in July and he has two Pit Bulls-a 1 year old male and a 7 year old female. We've had them together a couple times so far and they seem to get along okay. The male Pit Bull can be more aggressive than the other three dogs so my question is what is the best way to get the dogs acquainted so we can best avoid a serious problem in the future? Also, both male dogs will be kenneled when we're not home.