Before booking rooms, be sure to know cancellation

policy. They could have different cancellation policy and even the same hotel/travel could have different cancellation policies depending on rates. Expedia for example has an advance payment option, which you can't cancel the reservation.

Generally, reservations ahead of time save you time and money. I have had experiencs many years ago, spending time on a payphone (before the cell phone age) trying to find a room as night falls. You don't want to be stuck in that scenario.