Just of note, should you eventually get a 3DS or 3DS XL, definitely buy and use screen-protectors.
I normally don't care for screen protectors (getting bubbles out is usually a bitch, and I tend to cause very little damage to screens, even with a stylus), but with the 3DS you will want one.
The bottom screen of the 3DS and XL is smaller than the top screen (same height, smaller width). It is also raised up from the base of the 3DS, mainly to provide room for the Back/Home/Start buttons.
The raised square that surrounds the bottom screen has a small lip to it as well, raised a couple millimetres further up.
These lips rest touching the top screen, and being the full height of the top screen, touch it in two perfectly straight lines right up the height of the top screen.
These lips mean that whenever the 3DS or XL is closed, or any pressure is applied to the closed device, the lips will rub and scratch into the top screen.
To begin with it starts as a light mark which you can rub away, but eventually given enough time, it'll leave two permanent deep scratches about a quarter of the distance in to the screen from either side.

They can quite easily ruin the 3D effect, as well as the general look of your games.
A screen protecter is an absolute life-saver for this.
And another tip, albeit one that is more of a nuisance, is to leave a cloth in your 3DS whenever you close it, to completely seperate the two sides.