Just a hint in general: most hotels that have in-house reservationists have them on duty only 9-5 M-F. Outside of those hours, even if you call the hotel and ask for reservations, the call will be forwarded to Westin Central Reservations (or whatever central call center your hotel uses). They won't have local info most of the time.
I say to try the walk in method. If they have plenty of availability, you should have a little room to negotiate. Nicely ask for a supervisor or manager - they will be the ones to negotiate with (FDAs don't have all that much independent power).