I had a pair of Etymotics ER-6's. I only used them on airplanes, and they worked exactly as advertised; they cut noise far better than the active noise-cancelling Sony's I formerly used and they sounded fantastic. I'd have to pull them out when the flight attendant was asking me a question because I couldn't hear a word.

On longer flights, when I generally try to sleep, I found that I could turn my head sideways and sleep, but my ears eventually got irritated having these foreign things stuck in them (although it helped somewhat to make sure the cord coming off the drivers wasn't adjacent to any skin).

Then, I stupidly left them in the seat pocket in front of me, which I didn't notice right away, so I couldn't have tried to get them back. Sigh. I think Sony has some headphones of a similar style to the Etymotics but for less money. You might want to check those out.