Interesting post, GumGuy. I only wish you had thought to use it as the start of a new thread, cuz you'd probably get more responses that way. Perhaps one of the moderators will move it to do that?
Anyway, there are many books that would meet your needs. Two I would consider are:
The Williams-Sonoma pub, New American Cooking. It's subtitled "the Best of Contemporary Regional Cuisines." I don't know it the recipes actually are the best, but there are some great inisights into regional American cuisine. Oxmore House is the actual producer of the book.
James Peterson's Cooking. Although not, strictly speaking, American cooking, it can be summed up as Western for sure. And the near encyclopedic coverage of ingredients, techniques, and illustrated how-tos (there are something like 1,500 photos) might be perfect for your guests.
For an understanding of American ingredients and how they are used, I would definately take a look at Wiley's brand new, The Visual Food Lover's Guide. This lavishly illustrated book includes info on buying, preparing, and storing more than a thousand types of food.
Hope this helps.