i'm getting an ipad4 cellular soon...my wife will use it to read ebooks...i presume they can be downloaded and then deleted when you're finished with the book...not sure how much video or photos i'll download into the ipad from my cameras...anyway, just as a general capacity question, is 16gb too little, is 32gb about right and is 64gb a capacity overkill?...will i regret it if i don't get the max capacity?