VS has very limited upgrade availability. I think on expert flyer you search for G class award seat availability. One way to at least secure the Delta flight is book now and then call daily until the VS seat opens up if ever. Flying on AF/KLM is much easier for GUC as it just needs Z fare class available which you can generally see just booking a dummy cash ticket. Both require calling. I really like flying AF J for the seat, service and food. Can't wait fo try their new J seats. Also I would try to avoid the VS 787 and get on the A350. It's old, odd and just not that nice compared to the modern products. LOVE the LHR clubhouse, so looking forward to doing that next summer for my Paris Olympics flight.

Finally, don't forget that AMEX Plat people can get pretty good discounts of PE/J bookings via AMEX travel. Usually I save $200-400 per ticket for the same flights.