I definitely agree with the notion of going with as much memory as you can afford. The iPad 3 was my first tablet purchase, and I went in with the intention of just surfing the web, emails, ebooks, and downloading a few apps. My MacBook Pro will be my main computing device, and my 16 gig iPhone 4s stored most of my photos. Because I've only used up about 12 gigs on the iPhone, I assumed that 16 gigs was all I need for the iPad.
Boy was I wrong... I'm spending more time on the iPad than my MacBook, and I'm seeing that applications are starting to take up space. The game Infinity Blade 2 takes up almost one whole gig!! I'm going to give my 16 gig to my fiancée (who'll use it just for web, facebook, email & YouTube) and getting a new 64 gig. If there was a 128 gig version out today, I'd get it in a heartbeat.