Anybody got any suggestions for cleaning up this kind of damage? Anybody had any experience they'd like to share? Relevant experience, that is.
You have three options to take care of that: 1. Buff it. Then get some matching touch-up paint and touch it up. 2. Sand the whole bumper and repaint it. Make sure to blend it well. 3. Buy a new bumper if you don't want to sand it. Repaint it. Blend it well. There ya go.
Hard to tell from the photo. A lot of the light-colored stuff looks like it might clean up with a nice cleaner/wax or a polishing compound. Anything down to the sheet metal, yeah, you could get one of those little paint match things and some fine sandpaper and blend it. Or you could put a bumper sticker over it. Or do what Kamel has suggested. He's actually professional advice. It depends on how much time/money you want to commit at any rate.
The issue here is that it's a lease that's going back very soon. If buffing and touching up will pass muster on the return inspection, then I'm all for that.