I've reserved a minivan for our return trip. I can't guarantee how many people will fit with all their gear, but it's supposed to be a minivan. I reserved it from the Hertz at the airport. I know it's not the closest, but not much is open on Sunday morning. So it might just be a quick morning ride for a couple of us to get the van.
At any rate, the way I figure it is this: as long as we get the minivan, we can always add another sub-compact if we have more people. The bikes can go in the van, and the overflow people can go into the car.