IAMAL and all that; but my understanding is that, assuming you avoid a few relatively obvious things you should be fine. At least in the case of employers spying on employees, American law and courts give the owner of the network pretty much free reign. I would imagine that the same thing applies here, as you own this network. You are most likely to get in trouble for using data you pick up this way, rather than for picking it up. Don't use people's username/password combinations to hack their accounts or represent yourself as them(even if they send in the clear) really don't use any financial information you should happen to pick up, if you think they are looking at kiddie porn make very very sure to keep your hands clean, etc. Other than that, though, you should be able to observe traffic on your own network to your heart's content.
