The ER-6’s, as previously mentioned, or the Shure e3. I bought the e3’s before my last trip to CA, and they worked like a charm – I couldn’t hear a thing around me. Crying babies – GONE. That pervasive airplane hum – GONE. Incipid overhead announcements – GONE. Well, you get the idea.
They’re expensive, but if you’re traveling a lot, they’re worth it.