If you read the 7D Review at The-Digital-Picture you see that Bryan Carnathan makes quite a few references to the need to increase the sharpness setting to "2" or "3" to match the output of many of Canon's other models (at the time the review was written). He attributes it to a stronger anti-alias filter. This makes sense as the 4.3 micrometer pixels on the 7D's sensor are closer together, and thus a higher frequency, than the other models he compares it to.
When shooting with my 7D I normally select the "Standard" picture style which includes a sharpness setting of "3". After importing the RAW file to Digital Photo Professional (DPP) this setting is used to initially display the photo. In general, I sharpen using the "Unsharpen Mask" tool which replaces the in camera sharpening setting with the parameters I choose when the file is converted to JPEG or TIFF. Of course this is done non-destructively by adding a set of instructions to the file. The original setting is still attached to the file as well and can be restored by clicking the Return arrow to the right of the Picture Style heading on the tool palette (Even if you open a copy of the file made after you changed the settings later on a different computer).
Your final sharpen settings should be determined by the display size you intend for the image.
See also Recommended start point for sharpening RAW Images. There are a lot of variables that will ultimately determine your sharpening settings. The good news is that if you save your images as RAW files, you can always change it later if you want to.