Grand Pass, during most of the season, sees/holds more birds than most other CA's in the state. It is probably the best in the northern part of the state. I've been to Bob Brown, Nodaway and Eagle Bluffs as well. In the later part of the year before it locks up with ice, there are normally 100,000+ duck on the area. I would certainly hunt there again. But, once it locks up with ice they're gone, probably on the river or moving south.
Rest in peace my friend... Mocha- Jan 20th, 2001-Feb 1st, 2009.