I have a 2G iPad with 16GB and find it to be woefully inadequate. Even though I am a fairly casual user, I still find myself having to delete rarely used apps, movies and music to get things to fit. 32GB would be a bare minimum if I were to upgrade.
but thats the point (for me) the difference between 16 gig and 32 gig is storing more hardly used games.
ive a 16 gb ipad 4, i use it extensively for tv and films but use Plex to stream from my computer, even when away from home as it works fine over internet.
i play a lot of music but have itunes match, a bargain since ive got 150 gigs of music so i get about 3 years of itunes match just for the cost of an external drive to back up my music,
books dont take up much space, nor do apps. photos are all in dropbox, and since dropbox doesnt have huge free space, i use box.com to store magazines and move them as and when i want them.
so the only thing that takes up space is games. i have tons of games. cant stop myself buying them, and yes then i do run into space problems so i delete games to buy new ones. at the minute i have on my ipad about 16 games, taking up most of my space. but tbh for all the 'big' games i own, i dont play them much. the games i play most are all simple and small like snooker.
so if i had a 32 gig machine, all that would be different would be that instead of having a dozen big games i dont play much, id have 32 games i dont play often. and id still be deleting things.
it is a shame that ipads dont take sd cards but tbh dropbox has pretty much filled that gap for me.