[the number of people using scooters] has a big impact on how wide/narrow your facility space can be

Quite the opposite, in fact. The more spread out your facility is, the more people need scooters. 3500 people at Anticipation needed 20 or so scooters between them. 1/3 of those same people at Boskone (and that's probably the con with the most overlap) needs two or three.