Generally I think the iPod Touch is best at granting a large 'footprint' to control surfaces. Yes it's touchscreen and lacks any sort of haptic/mechanical feedback, but its screen is large and generally its onscreen choices are reasonably easy to read. I may not be in a retirement home, but I'm definitely challenged with my near-sight vision, and I've yet to have any visual clarity issues with my Touch. Plus it's Audible compatible.
Now as to how easy it is to manage and download...well, someone else will have to attest to that. I still do books the old-fashioned, traditional way.
My elderly grandmother who can barely see is in a retirement home and in the past she used to read 3-4 books a week for most of her life. I'm thinking of using Audible.com to allow here to listen to books on tape instead of squinting to watch television/DVD's. I'm looking for something with good sound, but very easy big buttons and very easy download and organization for a Senior Citizen. I don't think a standard MP3 player, (i.e. iPod, Zune, laptop, iMac) would work for her.
Any suggestions for a player to buy?
A "Jitterbug" type MP3 player if you will.