I flew LAX-LHR back in October. I used miles for upgrade LAX-LHR and got op-up on LHR-LAX. I would say it is very worth it for the long flight over as sleep is important to me and arriving relaxed was great. I spent the reat of that day and night out in the city (not tired). A nice dinner, movie and 7 hours of sleep really makes a difference. On the way home, unless you have miles to burn or get an op-up, I'd go for a good econ+ seat. Meal is nice in business but I usually watch a few of the movies and take a nap (2-3 hours) but no extended sleep for me.