Anita - I live by myself, so needing to work around someone else's schedule doesn't affect me. (Just the cat.) Otherwise, I might feel differently about the desk.
Sky2Evan - Nope, sit pretty much as if I were just sitting up from being asleep. Laptop on folded blankets at the foot of the bed, a small bookcase to put the computer on at night/when I want it off the bed at the end of the bed. (Also handy for mugs of water when I'm getting up, otherwise I just prop them next to me nestled securely in blankets.
I tried back against the wall, but it doesn't work well with where my outlets are, and I already have enough gripes about the cat unplugging me. (MacBook magnetic plugs have some good moments, but she'll rub against it and unplug it, too.) It's also easier to get stand up that way - just pivot, rather than having to put the laptop to the side, get to the edge of the bed, etc.
I do agree with the LifeHacker link - I can't stand to use the laptop flat on the bed. What I like about using the blankets (with a nice solid big hardcover or binder under the computer, to give it a hard surface for air circulation) is that I can adjust the height really easily - some days, one position feels a lot better than another, or I can shift the position of my wrists, etc.
But the chance to have the cat within 'reach out and pet me' range (which she is right now), to sit crosslegged, and to adjust position really easily (plus the fact I'm short, so my feet never touch the ground if I'm using a regular desk height) makes it a better choice for me, I think. Not necessarily best for anyone else, which is why I love looking at other people's workspaces.