The iPad is so much better with a keyboard. It's great without one when you're using iPad touch-optimized apps, but for more productive uses like writing papers or long-form blog posts, a keyboard really is a necessity. The Kensington KeyFolio Pro 2 is one of the best iPad keyboard cases I've seen so far, mainly because it's so adjustable to your needs.
For one thing, you can remove the keyboard to use the case alone. That doesn't really decrease the bulk, but it shaves a bit of weight.
Most importantly, you can position the iPad into almost any viewing angle you want, thanks to the clever velcro bottom of the iPad frame. So when you're in a tight airplane seat you can position the iPad at one angle or when you're lying in bed you can move it to another.
It's not completely perfect, but with prices now at about half the $99.99 MSRP, it's a pretty good buy.