Here's a follow-up: During my week in New York, I had a free Monday afternoon (museums are closed) so I bought four of the models discussed here:
Sharper Image $70 (headphones)
Brookstone $80 "
Sony $100 "
Sony $200 (ear plugs)
I tried them all out sitting next to my friend's air conditioner(!!), and decided I liked the Brookstone model best. It and Sharper Image seemed to me to work better than either Sony (an opinion confirmed in the specifications list), but I preferred Brookstone because the headset was a bit more comfortable, and covered the ear more completely. However, I discovered on the flight home that the earpieces are a bit large, and kept hitting the seatback when I turned my head to talk to my friend. Not a problem flying alone, or on a (relatively) shorter flight. And I had no trouble hearing her conversation.
Sony has a 30-day return policy, and the others are 60-days.