Captain Tim gets good reviews from hunters on the Refuge. Hunts out of Valdez, so you can drive or fly to town.
google will provide you with a few good hints. Kodiak at Old Harbor or Cold Bay for most seaducks using a guide. The Department of Fish and Game has a list of people that have listed themselves as water fowl guides. Lots of people on there you will never hear of advertizing duck hunts. To obtain trophy birds you need to hunt the end of the season and even then some birds may not be in full pulmage.