I'm looking to book an award trip next Fall with the current 20% off sale.

Playing around with availability, I had a choice of flying back from either Paris or London. The Paris flight, of course, went to London first. In fact, it would be the same flight out of London.

Taxes and fees when originating in London are about 50% higher than when starting out in Paris. Not sure if the difference is enough to justify leaving London for Paris (Chunnel) and heading out to CDG, but we're talking a couple hundred bucks here so it's worth running the numbers to make sure.