I would check out the wdfw's new waterfowling page, maybe do some google earth searches, fill up the gas tank and plan on spending a weekend driving around and learning some areas. Good duck spots are tough to come by and the best and most rewarding thing is to find your own spot. With that being said, the Potholes would be a great place to start but be careful out there and it can get tricky and you can easily get lost.