The difference between flying an 8 hr followed by a 15 hour flight in coach vs F is night an day especially when you are not able to take a shower at the connection airport and even take a nap in a quiet room. Basically in coach ones vaction starts when you get to your destinatiion and ends when you leave, in F (at least in BA F) you gain tow days of holidfay as the holiday starts when you get to the airport and when you get to your home airport on the return. I would never pay anywhere even close to 15K for an airfare but to earn those extra miles each flight to get the award ticket by being BA Gold (I am still a lowley blue tier myself)would seem more than worth it and indeed using mileage runs alone the difference in cost for a non elite and a BA gold for that $15k equivalent award ticket is $2k at a minimum.