Update: Deal still available at 8:30pm CT, Sat June 25 and low fares also from Philadelphia at about $60 to $70 more.
Delta PHL-Madrid $530 round trip into early March 2017.
One of the frustrating aspects about posting low fares is the transitory nature of these deals. You might be frustrated about not finding many of the fares I post on Loyalty Traveler and I am frustrated daily by the deals I write up and then do not post as the ticket prices rise, sometimes by more than $500 as I am writing up a deal. Yesterday I posted there were Delta deals to many airports in Spain and there were. But those fares changed within minutes of my post. This morning I saw lots of airports in Spain priced in the $400s on Google Flights, but when I followed the fare through to booking with Delta, they all increased to over $1,000.
As of 1:00pm CT there are several fares shown on Google Flights from Charlotte CLT and Dallas DFW to secondary Spain airports, those airports other than Barcelona and Madrid, which are now pricing in the $400s through KLM. This is an opportunity to book a ticket to airports like Valencia, Bilbao, Palma de Mallorca and other airports in Spain. The frustrating aspect for me and for you is these fares may not last through the time it takes me to write this post or may be gone within minutes or hours after I publish this piece.
Good luck if this is a ticket price that interests you. Book fast.
Here are prices I have found bookable online through KLM:
Important: Look for the Google Flights showing KLM/Delta flights only. Avoid Air France fares shown on Google Flights. These are low fares on Google Flights not bookable directly online in my fare search checks.
Here are four fares I found between 1-2pm CT:
Delta ticket Dallas DAL – Atlanta ATL – Bilbao BIO
KLM ticket Charlotte CLT – Atlanta ATL – Madrid MAD – Palma de Mallorca PMI
KLM Charlotte CLT – Atlanta ATL – Amsterdam AMS – Alicante ALC
As this post was publishing I was able to find a Delta/KLM/Air Europa flight that priced out as a Delta ticket in $400s, so check different options to see if they will price out online through Google Flights or Delta. Vigo in northwest Spain is one of the more remote airports in Spain, so most of Spain is pricing in $400s now.
Delta ticket: Dallas DFW – Atlanta ATL – Madrid MAD – Vigo VGO
Delta ticket: Philadelphia PHL – Atlanta ATL – Madrid MAD – ATL – PHL
$525.26 Sun Mar 5 – Mon Mar 13 (fare found at 8:30pm CT, June 25)