I do wonder if random selection couldn't give problems with getting really unbalanced teams, or preventing people who like to play together from ever getting that chance. Say your char bonds with another while waiting in the city or through some event, and then you'd really like to go on an expedition together to further flesh out that relationship with shared experiences beyond just
endless walls of rp some talking, that might be really difficult if it's truly random selection and there's a lot of players. Maybe some way where you can skip a sortie when you're chosen so someone else can go, but then for the next mission you are automatically (given the option to be) added to the team before the others are randomly added. And putting people in a list of people not eligible for new missions until the old pool is depleted (which runs the risk of the last expedition being under strength, though that could be hilarious in it's own right. Or just restarting the pool then but then not putting those people on the 'already went' list if they didn't go during the last pool as well).
More random locations ideas:
-location without gravity. Might be difficult to play straight for gm, but could give some interesting poritional gameplay.
-large muddy bombed-out fields (kinda like the cliche WW1 trench battlefield) with monsters made from barbed wire and pits filled with mustard gas. Watch your step.
-Imagine a very large and wide skyscraper. Now imagine someone pushed it over, perhaps over a large pit or swamp to prevent people just walking around it. Now you gotta navigate through that thing from 'top' to 'bottom', with lots of 'pits' (doorways) and difficult to reach passages, air vents to sneak through and all that jazz.
-inside Dev's head. This is the ultra-elite hard area, with literally no exit, because exits are for easy-mode scrubs