When Alexa recognizes your voice, stories and news items you’ve already heard will be skipped. To set up voice recognition, say “Alexa, learn my voice.” This is feature is especially useful if you listen to flash briefings on weekends when many flash briefings don’t post new content. With Alexa voice recognition enabled, you won’t hear the flash briefing episodes you already listened to.
If you want to do some casual research for a future trip, you can get fare estimates using the Kayak skill. You can say, "Alexa, ask Kayak where I can go for $400" or "Alexa, ask Kayak how much it costs to fly from Los Angeles to Dublin." The skill will ask for additional information and eventually provide you with a series of options and price ranges.