I think that traveling at all is a luxury for most people and I try to make sure my kids appreciate that fact. They know that the only reason we are lucky enough to do so is thanks to DD and DDF.
That said, I would definitely take my kids in J/F. As far as getting used to it, I think that as long as you explain that this is a treat and not always possible, it's fine. To be honest, I have a hard time flying Y (it's not just kids that can get spoiled!)