The other possibility, which I’ve done flying ABQ to BWI (some of which are non-stop) is a sequence like having to land in Dallas, then St. Louis, then yet another city, and then finally BWI without ever really getting off the plane because they try to get it turned around in 30 minutes. (If only they’d go with “plane turned around in 30 minutes or your flight is free.”)
Thanks for all of the replies! But I’m still not quite sure whether there will be a movie and meal service during the flight… 
Special thanks to everyone who has mentioned the early online check-in: I’m traveling with my father, and our best hope for being able to sit together is to be in the “A” group. I’ll be sure to check in as soon as possible, and will tell him to do the same.
I know to definitely bring food now, and there is also no doubt that I’ll be bringing my laptop on board: I have an adapter that will allow two sets of headphones to be plugged into one jack, so Dad and I can watch and listen to the same movie (assuming we wind up sitting together, of course). I always use a backpack when flying, so it’s no biggie to bring the laptop et al.
Regarding changing planes: like RealityChuck, the schedule for our flight shows 1 stop but does not specify an airport (whereas many other flights to/from the same places on the same day show 1 stop and do specify an airport). I’m guessing this means that we’ll stop somewhere, but will continue on the same plane.
Neither my father nor I are “of size” (yet, anyway!), but thanks, Veuve_ClicquotNJ.
Anne Neville: We’re flying into Oakland (from BWI).
Yeah, it sounds like you’re not changing planes. That’s very nice; I hate having to change planes.
Sign up for their Rapid Rewards program if you’ll be flying them with any frequency… and make sure that they have that number in your reservation BEFORE you fly on this trip.
Though this doesn’t apply to the OP, there is (or at least, there was) a non-stop flight between San Jose & BWI. On this flight they did serve a hot snack, but if i hadn’t eat breakfast before the flight, i doubt it would have been sufficient for the duration.
I do believe this flight is the longest flight that they offer.
Yep. Definitely landing somewhere and not changing planes. The good news with that is if you don’t end up sitting with your father for whatever reason, you’ll be able to change seats when you get to that stop and sit together for the remainder.
I know Oakland Airport well. There is a 360 Burrito stand in Terminal 1 (you will probably land in Terminal 2, but it’s a short walk between them) if you want to get dinner when you get to CA. That’s usually where I get food to take on flights that don’t serve it.
If you tell me where you’re going once you get to the airport, I can give you directions for getting to the freeways or for taking BART, and maybe recommend a few restaurants that are reasonably close to the airport (or to where you’re staying).
c_goat, it’s good to know that we’ll get a second chance to sit together if it somehow goes wrong when we board at BWI. 
Anne Neville, thanks for the info/offer! However, it will feel like 10:30pm to us by the time we land in Oakland (and probably closer to 11pm by the time we’re done with baggage claim), so I think we’ll just be ready for bed. We’ll bring substantial food with us on the plane, and eat dinner in the air. That night we’re staying in a hotel near the airport, and my father has directions.
The next day we head to Monterey, Saturday morning we drive to San Francisco, and Sunday night it’s back to Oakland so that we’re nearby for our flight out on Monday. Dad and I are both kind of geeks about maps and directions: I have a bunch of maps already, and he has a portable GPS unit that he’s already plugged our main destinations into.
I wish I’d known all this stuff before we flew SW from Baltimore to Phoenix and back in December - will definitely file it away for our next prospective jaunt. Fortunately we knew about the lack of food and had packed plenty of munchies and entertainment for the kids!
One comment on the open seating - we were travelling with kids. On the way out, the flight was uncrowded enough that we had no trouble getting seats together. On the way back, we’d have been totally SOL if I hadn’t had the foresight to injure myself badly enough on vacation that we got to preboard (see, I knew there was a silver lining to that!). Does Southwest make any effort to help passengers with reseating requests when the alternative is to separate parents and kids? In our situation, the kids weren’t young enough to get preboarding privileges (the announcer said “4 and under”, I think). They were, however, young enough to have made seatmates miserable had they been seated apart from parents.
They would probably ask on the PA if someone would move to accommodate some people who want to sit together. I’ve just asked people myself before when I was travelling with a couple and we wanted 3 seats together.
Let me take this opportunity to tell you how much I love JetBlue!!
I fly regularly from Virginia (Washington Dulles) to California (Sacramento and Oakland). I can usually get a non-stop flight for around $100 each way!
The BEST thing about them is they have TVs in the back of the seats with DirectTV sattelite TV, like 30 channels! And a live map that shows the country with a little plane moving across it so you know where you are, with your altitude and speed. So much fun!
While they don’t serve meals, they have unlimited beverages and snacks.
You are assigned a seat, and you get to pick your seat.
I love JetBlue. Why take Southwest?
I’ll second this. I find myself flying to Dulles more than BWI when I go back to the DC area these days, because I like JetBlue and their TV’s so much. I think they have better snacks than Southwest, too.
If JetBlue goes where you want to go, great. From here, they only go to four places directly, and they don’t go *at all * to where I’d be likely to go for family or business. (Chicago, Phoenix and Minneapolis)
Because my father is paying for the trip. 
True, but they are expanding their routes, so maybe they will start flying to those places eventually.
Sadly, I used to take the JetBlue flight from Sacramento to Dulles all the time, but they recently cancelled that route. Now I have to go from Oakland, which is a bit of a farther drive. They better NEVER cancel the Oakland-Dulles flight!!!