For winter travel, fly from Philadelphia to Madrid for $288 roundtrip on Delta.
As an example, I found seats departing Philadelphia PHL on Wednesday, February 13, returning from Madrid MAD on Wednesday, February 20.
You'll find other dates are available for travel from mid-January through mid-March. A minimum stay of 7-nights is required.
This is a Basic Economy fare, which only includes carry-on bags and does not include advanced seat selection. A checked bag costs $60 each way. The upgrade to a Main Cabin Economy fare, which includes one checked bag and standard seat selection is $180 more roundtrip.
See our fare details for booking info.
Need a hotel in Madrid? Here's what's available for the above dates on Hotelwatchdog.