We meet every Sunday at 4:00pm. 6 of us are married couples with small children/babies, and 2 of us are not. Gaming is a slow, stuttering process because of the kids, but that's why we started our own gaming group specifically for family people - we all expect it.
Usually we play until 8:00pm or so. Sometimes 3 of our members have to leave early to go to a book group at 6:00pm. When this happens we declare a "lack of quorum" (see below).
Quorum: if 2 or more people are missing, we play board games instead of D&D. We like complex strategy games like Settlers of Katan and Tikal. We also like anything by Cheap Ass Games.
We pick up 3 pizzas, some bread sticks, and four 2-liter sodas before each game and everybody puts a few bucks in an envelope in the kitchen.
We use D&D 3.5 rules, sit around a large dining room table, and have a nice, homemade battlemat in the middle (hard, transparent plastic with grid scored on with a razer blade, dry erase safe). I used to use a DM screen but then I couldn't see the battlemat, so I gave it up.
We have kids shows playing constantly in the adjoining room, hoping to distract the munchkins enough for us to get in some good, solid gaming. This has varying degrees of success, depending on how cranky the kids are.
After most people leave a couple friends usually stay and hang out until 11:30 or so.
Somehow we managed to find a group that is not only mostly parents of young kids, but also all Pagans or Wiccans (don't tell Jack Chick).