We use 66A some times in the marina moving around other boats. Chanel 9 is really used for all hailing now 16 is distress use for the most part. Here is the full marine Chanel list.
U.S. VHF Channels - USCG Navigation Center
FCC list on channel use FCC: Wireless Services: Ship Radio Stations: Data: Channels
I keep my boat on LBI.
i have never used ch9 for calling besides most people who monitor the radio have it on 16 in case there is actually an emergency. after all you are required to assist if they are in danger unless it puts yourself in danger as well