American Century CookbookLamington:
Your description of what you are looking for suggests that you might want to look at The American Century Cookbook by Jean Anderson. It is a combination of food history and cookbook, that gives some historical information about the origin of many popular recipes from the 20th century, along with recipes for those dishes. I found this so interesting - since along with food, I'm also a social history buff - that after reading through it myself, I went out and bought copies for my sister and several of my friends that are cooking enthusiasts. The recipes in it are obviously not cutting edge, and they are not especially regional, but they fall into the category of "old favorites," which is what I understand Rosengarten's and Cunningham's books to contain. I found that Amazon.com carries it after doing a Google search for the title.
If you are interested in something thick, and with a more regional orientation (and also not cutting edge, since it was published in 1980) the New York Times American Heritage Cookbook might also help you out. I didn't look to see if Ebay might have a copy, but with a 1980 pub. date, it's obviously out of print.