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Airfare deals are typically only available on limited dates. We recommend that you use Google Flights to find dates to fly, then book through an online travel agency, such as Orbitz or Expedia, which allows you to cancel flights without penalty by 11pm Eastern Time within one day of booking. However, if you’re using the American Express Platinum Card, you’ll need to book directly with the airline or through Amex Travel portal to get 5x MR points. Remember: Fares may disappear quickly, so book right away and take advantage of Orbitz or Expedia’s courtesy cancellation if you’re unable to get the time away from work or family.
We’re currently seeing great fares to the seat of the European Union on both Delta and Star Alliance partners United and Brussels Airlines. Delta is offering cheap tickets from New York (JFK), and you can fly on Brussels/United from Denver (DEN). We’re seeing fares as low as $368 round-trip, valid for departures from early October through early May 2018. Brussels (BRU) is a major Star Alliance hub, so you can opt to spend a day or two in the city and then continue onward to more destinations in Europe, or you could hop on a two-hour train ride to Amsterdam. Use Google Flights to select your desired travel dates, and then continue to the airlines’ sites to complete booking.
Airline: Delta, Brussels Airlines and United
Route: JFK/DEN — BRU
Cost: $368+ round-trip in economy
Dates: October 2017 — May 2018
Booking Link: Orbitz
Pay With: The Platinum Card from American Express (5x on airfare), Chase Sapphire Reserve, Premier Rewards Gold Card from American Express, Citi Prestige (3x on airfare) or Chase Sapphire Preferred (2x on travel)
Here are a few examples of what you can book:
New York (JFK) to Brussels (BRU) for $368 round-trip on Delta:
Denver (DEN) to Brussels (BRU) for $389 round-trip on Brussels Airlines and United: 
Maximize Your Purchase
Don’t forget to use a credit card that earns additional points on airfare purchases, such as the American Express Platinum Card (5x on flights booked directly with airlines or American Express Travel), Chase Sapphire Reserve, American Express Premier Rewards Gold or Citi Prestige (3x on airfare) or the Chase Sapphire Preferred Card (2x on all travel purchases). Check out this post for more on maximizing airfare purchases.
If you’re able to score one of these tickets, please share the good news in the comments below!
Source: thepointsguy.com