One of the most important pieces of travel advice I received as a new mother was to pack a length of duct tape wrapped around a pencil to use for babyproofing a hotel room. I used it to tape washcloths around the corners of a sharp coffee table, cover electrical outlets, and secure lamp cords among other things.
Some hotels, like the Breakers in Palm Beach, will babyproof a room before you arrive or upon your request. It's always a good idea to ask when you make your reservation if babyproofing supplies are available. And if they don't, bring the duct tape!
Any readers have other suggestions for easy-to-pack items that can help babyproof a hotel room?