i'd wager to say i think BA first is the best option to the US these days.
in addition to what others mention above, ensure to leave yourself a few hours in the CCR before to enjoy everthing, relax, dine in the dining area and have some champs or espresso martinins (im very basic).
on board, i have no qualms asking for whatever if you not offered, like slippers. but during the flight, depending on the crew who can sometimes retreat to the galleys, i have no issue with the call button--which i know has been a bit debated on here. but the point of the service is to provide you with whatever you need so long as you are not obnoxiously drunk lol.
oh and when you are ready to nap, be sure to ring that bell and ask for your bed to be made up which i do when i'm off to the loo....and enjoy!
i cant remember my first first but i do remember my first business on VS in the early 2000s when i was just out of uni and randomly upgraded at check in...it was the best experience ever...even though in hindsight it was a very mediocre seat but with endless wine and a massage therapist on board, it was wild to me!