4) Go HBO.

OK, I think it will be OK to get one labelled to LHR and the other to IAD, your option 3. The baggage system is fairly dumb, it's not fully plumbed into your reservation. There's always a risk that bags don't make it, particularly on connections, so pack accordingly. Hence If you were wanting clothing for the overnight into Sunday I would personally carry that, since if that didn't pop out in LHR (highly unlikely) then I guess that would be a big nuisance. Checked bags shouldn't have anything in them critical for the next 48 hours in the ideal world.