Ok, so I think you are misunderstanding the meaning of the game's settings here.
The default resolution in which the game was created is 320x200, and the available Direct3D options for the graphics basically scale that original resolution to 2x / 200% (640x400), 3x / 300% (960x600) or 4x / 400% (1280x800) with or without anti-aliasing, which is used to smoothen (= blur) the edges of the pixel graphics, should you prefer that.
In terms of aspect ratio, these are all 16:10 resolutions, so unless that is the aspect ratio of your laptop's screen (and in my experience most modern laptop screens use 16:9), there is no way to have the game "cover the entire monitor" through these settings. There might be ways to achieve this through your video card driver's scaling settings, but this will result in the game being "stretched" to fit your monitor's aspect ratio.
Now, in my opinion, to make the game look its best (ie. make the graphics look sharp and crisp) and have it fill the largest possible area of your screen, you'll first need to figure out -- as doady said -- if your laptop is capable of displaying a resolution of 1280x800. If it is, go with the 4x nearest-neighbor filter. If not, choose the 3x nearest-neighbor filter (960x600). This will result in the game covering most of your screen, with a black border around it, and in the correct aspect ratio / without stretching. This way it looks great and is perfectly playable.
In addition, you can turn off the "Smooth scaled sprites" option which blurs the edges of the character sprites when they are scaled -- for example, when a character is walking down a street in a northern direction and is scaled to look smaller and smaller the further they move away from you -- in my opinion the blurryness of the sprites looked "off" compared to the crisp pixels of the environment in these kind of situations. It all comes down to personal preference though... Once you find the resolution that works, you can play with the options a bit. I personally prefer games in this graphics style to look like the attached screenshot.