I simply plug it into the charger it came with; it's right by my desk, so it's pretty convenient. I wasn't even aware of the cradle for some time; I think, since I have the 3DS XL, I can only get one through Club Nintendo, and I may or may not have seen them in stock at some point.
I use the charging cord, since my 3DS didn't come with a cradle. (Got it a week ago, and was very confused when I didn't get one). I like that option of being able to place it on the cradle, so I'm going to get this one also.
I only use the charger for mine, and my sister uses the charger as well. She sometimes uses the cradle so that she can just put it down on her desk and be lazy by having it charge without doing anything xD
You know, until quite recently I never realised you could charge without the cradle attached. Since then, I always charge with just the charger wire and not the cradle device.