I don't want to lose a game because somebody in the vicinity turned on a poorly shielded microwave oven.

You shouldn't be using 2.4GHz anyway.

And there isn't much else that's likely to interfere out of nowhere.

If you're going to all the effort of getting everybody together in person, why not do it right and set up a wired network?

Sure, go ahead and buy a bulk pack of cables, but I don't think it's going to have a particularly large impact on a generic small LAN.