There is naturally a divide between pocketable or not. I personally visualize myself reading a book or news article and making notes with a mind-mapping app such as HiveMind and looking up locations on maps and referring to various web pages all at the same time. Doing this fluidly requires a certain amount of screenspace, so I have started thinking about ten inches as the size I need.

Since I spent my entire high school and college years carrying a spiral notebook of nearly that size, often schlepping everywhere by bus or hitchhiking without feeling oppressed, I don't see why carrying a tablet in one hand should suddenly seem like a terrible thing.

So I'm thinking small cheap pocketable cell phone and luxurious big tablet as the good combo for me.