I've got the same situation, 6 hives, suburbs. I still end up with a swarm or two, but using the above techniques keep them mostly controlled. Some of it is not quite being on top of the "keeping the swarm urge away", it is a matter of keeping the hives just a little bit weaker than ideal, as the others have described. And you can always combine later or try 2 queens in a hive.
There are a lot of opinions about hive strength and honey production, but I'd rather have a weaker hive and less honey than having a neighbor putting the kibosh on my "operations". But even still they produce more than enough honey, so that isn't much of an issue.