Keep in mind that boys are inherently movers and shakers. They express themselves, and their energy, much differently than girls do. My son seems to be about the same age as yours, and he is a well-mannered kid, BUT he is also very much a boy. This means when he gets with other kids, and not just boys, it's running around, chasing, good vs. bad, etc... There will always be some basic rules (no running inside, no hitting, etc...) but I recognize that it's very hard to get boys to sit still and be involved in something for a very long period of time. The length of time it takes to play a round of Sorry or Connect 4, to be exact!
When my son plays with my neices, he willingly takes part in playing house with the kitchen and the dolls that they have. The girls also willingly play tag and chase and things that are more typically "boy".
I'd say keep up with the playdates, one on one. Do recognize that boys aren't going to stay on one activity for the majority of the time, but you can lay down some ground rules (ie, no new games come out until the legos are put back) that will help. As for them including your daughter (I'm assuming here, you didn't specifically say this) and not shutting her out, let your son and his friend know at the beginning that although they are the friends, they should let his sister play with them if she would like, if that's how you want it to go.
I think the biggest thing to remember is that all boys, just like kids in general, are not the same. Just because your son has a calmer disposition does not mean all boys do,or should, as well. Likewise, just because some of the boys he has recently played with are a little wilder than you are used to does not mean that all boys are like this, or that those who are have bad manners or personalities that are "mean". Keep at it, and eventually you'll find a happy medium between your comfort zone and what (at least in my experience!) typical boy playdates are like.