Thanks for the responses.

I've been actively checking MMB and they are really pushing the POUGs. I am on a cheapie WT ticket and the current offer is £189 to WT+. However, this has been varying wildly. Sometimes it goes up to £500-800 to WT+. Sometimes it offers me a direct upgrade to F for a few thousand pounds. They really are trying to shuffle.

I'm a schoolteacher so I'm well aware that it's the school holidays. I fly at around this time to the USA every year and the flights are always packed. Good point about just one family not showing up and my whole plan falling apart though.

I suppose I'll just buy the cheap AA ticket, and if it turns out I don't need it, it won't be much of a loss.