Here is my process. Haven't had a oversharp or soft rejection in a while so I think it works well...
Using Photoshop CS5, I resize to final size which is either 1024x or 1200x on the wide end depending on the quality. Then I duplicate the layer and add one pass of USM
at 500%, radius .2 and threshold 2. If that is a tad too much overall, I'll adjust the opacity of the top later which controls the strength of the top layer. Usually though I leave opacity of the layer alone but I will create a layer mask and using the brush tool set to 30% strength and paint over specific areas of the photo that are oversharp. Then after that I will flatten the image and use the sharpen tool and 25% strength and go over areas that need a little extra kick. Nose, cockpit windows, and wing root/engine and pylon are areas that benefit from selective sharpening with the sharpen tool.
That's it! The trick is recognizing what a properly sharpened shot looks like on your screen. Due to differences in monitors, photos might look good on your screen but soft to the screeners or vice versa.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.