I guess there are at least two categories:

1. Those that are in another city, knew they were going to be there, and didn’t book ahead (or just need an extra room?)

2. Those that live in a city and decide to get a hotel room tonight.

I’m actually having a hard time figuring out who’s booking last minute (and why a site specializes in it) other than for parties (large groups or.... by the hour).

I’m like 50/50 with booking things in advance and not. Prices don’t seem to go up too much so sometimes I value the flexibility of not booking until needed.