Migration timing varies among different types of waterfowl. For example many states that are not "waterfowl producing" hold special teal seasons...which will actually come in a couple of weeks. This takes advantage of the blue winged teal migration due to the fact that they migrate through very early in the fall or late summer.
The brunt of most waterfowl migrate from late October through December. The Northern States hold there seasons from Oct.-Dec., and the Southern States hold there seasons from Nov.-Jan. in most cases. It seems that the puddlers migrate before the divers...but there are always exceptions.
As far as the best States goes...that is very debatable as you'll see if you do a search on "Best waterfowl State". It can vary with the time of year as well. Early in the migration the northern States such as ND, SD, MT will produce well, and as the season progresses and the birds move farther South, the Southern States such as AR, LA, MO, TX will produce greater numbers. A lot of this is dependent on the numbers of hunters as well.
If I were to come to the U.S. specifically for a hunt I would probably focus on the Mississippi or Pacific flyway.
Maybe someone else can chime in with some more info for you.
Vegetarian = Old Indian Saying "Not Good Hunter"