I owe a humble thank you to an unknown rodent!
This shirt, which I planned on altering, was too big for me to begin with, and the neckline was too low. I figured I would have some extra fabric to work with, and it's a good thing I did. After I washed it it was fluttering dry on a chair in my backyard, but I forgot to bring it in for the night. When I went out to get it the next morning, I discovered, much to my annoyance, that some little rodent had ripped holes right in the front of the shirt! I tried to sew them shut, but the result was obvious and ugly.
I sliced out the rodent holes, which hit around waist level, and took in the sides and sleeves of the shirt. Then I gathered the bottom portion of the shirt to the new width.
I sewed the gathered edge onto the shirt to create a peplum, and also made two pleats in the neckline to keep it from gaping. It's now one of those throw-it-on-and-feel-great-about-the-casual-prettiness-of-it kind of shirts.
Frankly, I don't think my original, vague, alteration plan would have turned out as well, so sometimes frustrating situations force out better creative results.