I find it very easy to fly into London, stay a day or so and then go on to my final destination.

I just booked seats from LHR to MAD for less than 80 pounds roundrip.

This type of routing allows me to stopover ( in this case I'm taking my sister to Washington DC for a few days), stay a few days in London and then take the flight of my choice on to Madrid.

Have done this several times and although I could use award all the way -- find this much more convenient. More options, can fly from Carlsbad instead of San Diego (free parking), etc.