First of all, if you are interested in illusions I would recommend that you pick up all the books by Jim Steinmeyer. Currrent book is " The Complete Jarrett". Also look for "Art & Artifice", "Device & Illusion", and "Modern Art". Steinmeyer's the best.
Now, concerning the books you asked about, these are the ones I've owned (or currently own) and can comment on:
"Genii Illusions" has a few interesting illusion ideas reprinted from Genii magazine of years ago.
"Illusions for Princes or Paupers" - Eugene Poinc -------
Gene Poinc is a very creative and stimulating writer/creator. Anything by Poinc is worth reading.
(Poinc's web site is hosted by The Learned Pig Project. TLPP posts public-domain versions of magic books. Go to their web site to register for membership and you get all the TLPP books , plus access to Gene Poinc's web site: http://thelearnedpig.com.pa/
Griffen's "Illusion Show Know-How" contains some great info. on trouping and selling a classic "full-evening" magic show. The information is somewhat dated. It's more interesting as a record of what used to be than what currently is ....... Venues are changing and methods of booking are also a little different than when the Griffen's wrote their book. Still, it is a worthwhile effort from someone who really did it ; really made their living in this field, so it's not just empty theory. Another caveat: "Illusion Show Know-How" is currently published by Abbott's. Abbott's does a terrible job on the production of this book. It looks like it was produced from a xerox copy of a xerox copy. The type is sometimes illegible and some of the photos are worse than useless.
I rembember the original edition of this book being much more clear and crisp (both photos and text) so I assume that over the years Abbott's has misplaced the original plates and is relying on photo-lithos of a copy of the original book. Try to pick up a used copy "cheap".
Byron Well's "Great Illusions of Magic" is a reprinting of some standard "workshop plans" of classic illusions (such as Asrah, Thin Sawing, etc.) from Thayer, Tannen's, Abbott's , etc. Not a whole lot of material on illlusion philosophy or presentation. Just the inner workings ("guts") of the illusions. I recall that most of the plans come from Tannen's. It's "OK" if you can pick up a copy "cheap" on eBay or something. Don't pay the usual "$100.00" asking price. Better to spend your money on the Paul Osborne illusion books.
My 2 cents worth.
[ September 08, 2001: Message edited by: Dai ]