To add another datapoint:
Had a Wednesday night reservation for an Intermediate (C), and got an Ultimate Choice/5* notification a few hours before arrival.
PC area had a low-spec Camaro, a couple generic Altimas and Elantras, one Maxima, and, oddly, a Nissan NV Cargo van. Nothing else.
5* had several base spec Altimas, several base spec Elantras, one Cruze, one older Impala, and several Malibus. I took a "younger" Malibu - fairly base trim but with working XM. Area was maybe 15-20% full, at best.
I was hoping for some kind of small SUV.. the only thing they had in the "fallback" zones was a really tired looking Jeep Compass.