If you aren't a cultural anthropologist, you might not have heard of "leave-taking behavior" before, so let me explain. It's basically a fancy way to talk about how people indicate, both verbally and non-verbally, that they are going to depart from the company of whomever they're presently with. This culturally-conditioned behavior is taught to us as children ("Wave bye-bye!" "Give grandma a kiss goodbye," and so on). And so far in my experience, I've observed some notable differences between Southerners and Pacific Northwesterners in this regard.
*caveat* All of my anecdotal observational data comes from interacting with friends, not family members. I suspect that familial leave-taking behavior may vary. My own extended family has rituals like going around and personally saying goodbye to everyone present. But since I don't have any relatives in Memphis and I hardly ever hang out at other people's family gatherings, I have nothing concrete to report on that topic.
1. Length of time it takes to leave
From the time someone first says, "We probably should be going" to when they actually walk out the door, how long does that usually last, in your cultural context? Factors that may influence behavior: the total number of people present, the type of activity, the intimacy of communication that has been experienced thus far, and the importance of timeliness to the person's next engagement. So far I think the record that I've seen in Memphis is about 40 minutes. This happened at our apartment when we had 2 other couples over for dinner. Around 8:30, one person asked their spouse what time it was and commented on how they should probably get home to the kids. The other spouse agreed. But, they didn't get up from the table and continued talking. Eventually we all collected dishes to take to the kitchen, and the conversation shifted to something else. It had probably been about 15 minutes by this point. Spouse #1 again mentioned that they should be heading out. The other couple agreed that they needed to leave, too. Then somehow a gender divide happened, with the women talking in the kitchen and the men in the living room. Again, about 15 minutes passed. Spouse #1 gathered their belongings and started moving towards the exit, but spouse #2 needed to use the restroom. Finally, goodbyes were said all around and the first couple left. The second couple stayed a few minutes longer before also heading out the door.
Interesting, isn't it! I haven't experienced this long of leave-taking behavior in Seattle. Usually, I would wait until the time I actually need to leave, then say something to the effect of, "Well, it's getting late" or "we have to get up early for work tomorrow" or even just "it's been so great to see you! We should probably be heading out." Then within maybe 5 minutes, I'd be gone.
I think the longer leave-taking behavior ritual may symbolize a level of comfort or familiarity on the part of Southerners, that you don't feel like you need to rush off after your designated activity (in this case, dinner) has finished. But I don't understand why they would announce their intentions to leave so much earlier than they actually walk out the door. In my cultural upbringing, you wait until you actually have to leave, and then you go. It's less drawn out. And perhaps, less friendly? I will say that when these people took a long time to leave my house, it made me feel like they enjoyed our company and were not eager to depart. I felt the same way about my friends in Seattle, but I would have probably communicated it verbally, by saying "we had such a great time! It's always so fun to hang out with you," etc.
2. The importance of being on time
I really don't have enough data to fully expound on this point, as my main frame of reference is church. The people in our Sunday School class (yes, in Memphis, adults go to Sunday School) arrive at class at least 10 minutes after the scheduled start time, and then we don't leave on time to get to the church service. After class is over, the culturally appropriate behavior is to talk to the other people about whatever is on your mind, including but not limited to college sports, the Grizzlies, upcoming social events, people's children, the weather, what restaurants you've been to lately...just general life stuff. I like to get to the church service for the singing part at the beginning, but I feel kind of awkward being the first ones to leave. So we usually stay and chat for awhile until the conversation starts to die down.
Also, the church has two services with Sunday School in between, so some people are just going to be heading home after class and aren't in a hurry to leave.
The exception here might be parents with young children that they have to go pick up from the nursery. Young children's impact on their parents' leave-taking behavior is a subject for other scholars with more first-hand experience, though.
3. Group normative behavior
Here's another anecdote for you. A few months back, some friends invited us over for a game night. We knew the one couple who was hosting, but we hadn't met any of the other attendees before. We'd eaten snacks and played a couple group games. One game had just wrapped up and we were deciding what to do next when, all of a sudden (in my perception), two people said they needed to get going because they had to get up early in the morning. Then all of the other guests (about 8 total) all hopped up saying that they needed to leave, too. In about 5 minutes, they were all out the door. I was surprised! I had never seen a group of people leave so quickly in Memphis! D.F. and I stayed to play another board game. When we were setting up the game, we looked out the window and saw the other party-goers standing in the driveway, continuing a conversation for about 10 minutes. Aha! My theories about the South prevail! These people couldn't resist the pull of Southern leave-taking rituals that one does not simply bid a group farewell and then depart. No, it is important to extend the gathering and conversation for an appropriate amount of time, even if that means standing in the driveway talking in the dark.
I'm sure I'll have other observations as time goes on. And if you are one of my Memphis friends and recognize yourself in these stories, I hope you don't mind me studying your behavior for anthropological purposes :) I just find y'all very fascinating!