Is the F in AA so good that it will be an experience in itself? If I do that, AA to ORD and BA from SFO would be logical, as AA doesn't fly SFO-LHR, at least not on my dates. Will I lose a lot of the BA F experience when flying F on a night flight? And will I lose the Concorde Room? As I understand, one has to travel BA F to get in (not AA F) som I will not be getting it on the outbound. But will I get in on the inbound, connecting from BA F to CE? I have seen something about "major part of itinerary deciding lounge access", but does that apply here?
Welcome to the BA forum
ksu, I had always assumed we were the dark side actually. Personally I'd go for the cheapest arrangement that is convenient and has one BA First section in it. You can regard it as a taster since there will doubtless be other opportunities in the future if you like it, and if you didn't like it you would be annoyed at having a second trip and paying extra for it.
For the Concorde Room, yes if you leave via AA you leave via T3 and so no Concorde Room, but you do get Galleries First which isn't bad. Back to Norway, yes it is merely sufficient to arrive by BA First and then depart the same day on a BA flight from T5 anywhere, it's not the "major part" thing, if you did First from Moscow then economy to Buenos Aires (God help you) then you'd still get Concorde.
If you can sleep in SAS Business then Club World alone would work very well for you, everything else would be a bonus.