Somebody else mentioned a Hemingway guided tour. There is also a book titled 'Walks in Hemingway's Paris' that describes a number of sites specific to that author's Paris sojourn, but also sites pertinent to many of his ex-pat contemporaries. It's interesting how much the paths of all these individuals crossed.
I think Paris must be the most written about city in literature. Granted, you and your friends aren't likely to have time to read some of the great books set in Paris, I'll recommend a few anyhow. 'Cousin Bette', by Balzac, details a walk that the eponymous character takes from the Right Bank to the Left that takes in a lot of sites. I managed to trace most of the route on a map of Paris. 'Les Miserables' by Victor Hugo is a great dense tome, but gives a great picture of Les Halles and the Marais neighborhoods during the June Uprising of 1848. He describes a number of streets that the militants erected barricades on. 'Pere Goriot' by Balzac provides a vivid description of the area below the Pantheon in the 19th Century.
There are oh so many more examples to provide, should you be interested.