Matt "Dean Dad" Reed has a post about the issue of academic conference travel, which is expensive and often the first thing cut out of college budgets. Which leaves faculty either disconnected from their field, or paying out-of-pocket to attend meetings that they need to demonstrate their scholarly productivity. This, in turn, tends to skew research meetings even more toward those at elite schools with big budgets.
This is a hard problem to crack, because the issue isn't just money but time. Reed suggests dropping "the charade of the last half day" because it requires an extra night in a hotel to go to talks that are thinly attended because people are leaving early to get to the airport. But, of course, this isn't really a viable solution, because unless both your home and the meeting location are near big-city hubs, there aren't likely to be flights home you can catch without missing the latter half of the last full day of the conference. So dropping the last half day leads just moves the charade up to the afternoon of the last full day. Or you're paying for another night in a hotel anyway, before getting a morning flight.
There are some measures you can take to make the last day a bit less of a charade, but no really great solution to this problem. DAMOP has held a "Hot Topics" session on the last morning for something like ten years now, hoping to get people to stay for the last half day by running a slate of big-name invited talks. And it sorta-kinda works, except for airline schedules-- with the paring down of most flight offerings, there's frequently no way to make a connection back that would let you leave the conference at lunchtime.
This problem looms extra large for a middling conference like DAMOP, which runs around 1000 attendees every year. That's too big to host at most universities (it used to be run in college towns, and some people still lament the loss of that connection and the cheap dorm housing it enabled), but not big enough to fill a really big convention center in a major transportation hub. Which means it ends up in second-tier cities with medium-sized convention centers that are reasonably affordable. But those cities are often difficult to get to-- the most recent DAMOP was in Madison, Wisconsin, which is a lovely town but a huge pain in the ass to get to. This is especially acute when your home base is also a small second-tier city-- to get to Madison from Albany, the options are 1) to fly United through O'Hare, which is basically asking to spend an unscheduled night in Chicago, 2) Delta through Detroit, which is less likely to strand you, but adds to the travel time, or 3) Fly to Chicago or Milwaukee, rent a car, and drive more than an hour.
A lot of academic meetings are in a similar predicament. The APS March Meeting is at least an order of magnitude bigger than DAMOP, so it can be in larger cities with better transportation options. But that's far and away the biggest meeting going in physics, and most other conferences just can't afford more convenient locations.
This isn't a problem unique to academia, either. In the wake of the London Worldcon, I saw a blog post grandly declaring that There Should Be No More Back-to-Back US Worldcons. Ever. Which starts off with a lament that the next two Worldcons (in Spokane and Kansas City) will be in " a regional American city without a proper international airport."
And, you know, it's true that London was wonderfully easy to get to. London is also ruinously expensive, as are most American cities with "proper international airports." I suspect that this year's Worldcon was really only possible because the tourist infrastructure built up for the recent Olympics is still under-utilized, and was thus available cheaply. As it was, there were a number of issues that basically stem from trying to contain costs-- the too-small rooms for panels that led to a lot of lines and people getting closed out of stuff they wanted to see, for example. And the food prices were eye-popping-- the figures registered as "OK for overpriced conference center food" when I forgot to convert from pounds to dollars. Which is okay for a once-in-a-long-time-period Event if you have a good and stable income, as we do, but probably a lot less appealing if you're, say, a writer.
So, you know, you end up in regional American cities, which more or less by definition don't have "proper international airports." But those cities tend to have hotels and convention centers that are cheap enough for a convention of a few thousand people to book at reasonable rates and still have money left over to provide the expected level of amenities. For more or less the same reason that the next two DAMOP meetings will be in Columbus, OH and Providence, RI. With "Hot Topics" sessions on the last half day that I'll have to miss to get to the airport in time for my flight.
(Well, OK, I'll drive to Providence... But you know what I mean.)
(Another constraint for these things is the presence of absence of local organizers. This is less of an issue for DAMOP these days, because the running of the conference was turned over to the APS conference staff some years back. Still, the Madison meeting benefitted significantly from the presence of a sizable AMO physics contingent at the University of Wisconsin. It's a much bigger factor for SF cons, which by definition require teams of volunteers to put together bids and handle all the logistics. Which is why you do see Worldcons in big cities like Chicago and Toronto-- because there's a strong and organized fan community there that can deal with the hassles of running stuff in Chicago (which I'm given to understand were massive the last time Worldcon was there). You could probably get a Worldcon near the "proper international airport" in Detroit, for example, but I'm not sure there's anyone there who could put it together.)
Speaking to your last parenthetical, Detroit did pretty well holding this year's NASFiC. And there are a couple of long running annual regional SFF cons in the metro area. WorldCon probably isn't that far fetched. ;)
Slightly off topic, but the lack of decent air service to mid-scale convention facilities probably has its roots in the airline deregulation of the 1970s, which perhaps provided an unsustainable boom of air transport through the 1990s but which has been slowly collapsing ever since:
You could probably get a Worldcon near the “proper international airport” in Detroit, for example, but I’m not sure there’s anyone there who could put it together.
The airport in question is about halfway between Detroit and Ann Arbor, so if you have volunteers available in Ann Arbor, you could host a Worldcon there. No guarantees that those volunteers would exist, but it's less improbable than having such volunteers in a place like Spokane.
My major scientific conference is in San Francisco, and I'm close enough to Boston to fly from there. So in my case the "last half day" issue is solved by taking the redeye flight (I have learned from experience that taking an afternoon flight home to the East Coast is just as bad, and I don't get to enjoy the extra half day out there). But the issue still exists for most people coming from anywhere west of Chicago, and people who would have to wait in a hub airport for three or four hours to catch a flight home.
Not to mention that airfares increasingly favor major airports. BOS-SFO is a highly competitive market: there are four airlines to choose from, and that's if you insist on a nonstop flight. So you can get a reasonable deal on airfare, even if schedule constraints force you to specify what flights you are taking. There are two airports closer to my location than BOS (MHT and PWM), but to fly from one of those airports I would not only have to change planes but pay significantly more for my ticket.
I remember the last conference I attended in KC. Mid-week there was no place to eat at all near the convention center as the downtown shut down after 4PM. I avoid midwestern cities for that reason now.
If you live on the west coast, the travel problems are usually even harder, because many conventions of various sorts tend to be east of the Mississippi or near to it. Long flights, limited flight times, time zone changes, more expensive travel - all that stuff.