It all depends on what accessories you get. If you just use the iPad naked, then there are a ton of small sleeves that you can use, and many have shoulder straps and such. However, if you also have a keyboard and pencil, and perhaps stand or other accessories, then you will probably want something that holds everything.
I use in Incase sleeve which works very well for the naked iPad or with a thin back cover. I don't really have a need to carry my ipad somewhere by itself, so if I'm bringing it with me, it means I'm traveling and will have other things with me, so I put the sleeve in a backpack.