In addition to the strategies suggested in this thread, consider the idea of purchasing one-way business class tickets for the two of you with points for the trip to the UK and using points or cash to buy return premium economy or even economy for the trip back to the US. I generally follow this strategy in my own travel because I find myself more rested on the overnight flight to the UK, thus justifying the extra expense, but willing to accept an upright seat in premium economy or even economy for the day flight back.