If you don't already have it, I strongly recommend you buy Nick's book, 'The Strip-Built Sea Kayak', especially if you have already decided on building the Guillemot. He has a section on wood selection. I believe there's a link on this site to Amazon.com where you can buy directly.

But to answer your question, cedar is generally the material of choice for strip-building due to its light weight and easy-bending characteristics. White and red cedars are the lightest. The redwood you were thinking about is more brittle, so it is harder to form the more coutoured parts of the boat. The book recommends redwood for 'accent strips or darker hulls' and says 'mahogany is pricey and dense, but will produce a beautiful-looking boat.'

Hope this helps Dean