Get an 8gb touch for music/video/internet/apps and a 2gb shuffle for audiobooks. I always try to encode my audiobooks (I have hundreds of them) into a single bookmarkable file, and since 32kbps (mono, voice optimized) is usually perfect for them you cna put tons of material on a shuffle (days and days worth), and because they are just large single files you can find what you want really easily without a screen. Plus they're small, light, durable and cheap.
But you don't get the whole iPod experience with a shuffle, so get a touch, too. It's probably the most impressive piece of technology I've ever fit into my pocket. 🙂