This is a very interesting site with multiple pictures of all of the current Amtrak stations, and many discontinued stations, too. In both English and Japanese. Also has pictures of the Amtrak station in Vancouver, British Columbia.
USA RAIL GUIDE sorts stations alphabetically, by operational status, by state, and by train(s). The stations range from the open platform at Williams Junction, Arizona, to the glass shelter at Elko, Nevada, to the "Amshack" at Houston, Texas, to the modest brick station at Maysville, Kentucky, to the relatively large station at San Jose, California, all the way up to huge terminals such as Washington, District of Columbia, Union Station.
USA Rail Guide