I am just completing my Madrid day trip and loved every minute of it. All was very easy, I even managed to get into WTP for ET fare on the 767 outbound! If they come back, or you can find them hidden away, I would highly recommend doing one and Madrid is an easy option - if anyone wants any tips just ask.
Funnily enough, I need to fly to EDI tomorrow short notice for the day and have managed to get the 45 pound each way fare that they advertised as the daytrip fare there - and this is to travel tomorrow so they are still out there! As a comparison, I looked last night to do an overnighter and the price was nearer 400 pounds!!!
a slightly burnt person (Madrid was chuffing hot today) who swapped to an earlier flight home which is now delayed
aks120