I am posting this with a bit of apprehension, realizing that everything I ask in a way or another is answered somewhere on the BA forum, and having observed that this particular corner of FT is probably the one suffering fools least gladly...

I seek advice about at multiple stop trip to the US in October. This will be for business, I will pay myself, but will get the costs deducted as a business expense from my taxes. My routing is KSU-ORD-SFO-KSU, with stops of 5-7 days in both ORD and SFO. I will be SK Diamond when I make the trip (highest published SK elite level) due to weekly domestic commute. No status on any other alliance.

As I'm a big guy (183 cm/120 kgs) I had planned on flying business. SK gives me a price of NOK 25000 (~GBP 2500) in business for KSU-OSL-ARN/CPH-ORD-SFO-CPH-OSL-KSU. The price is OK, I know the SK product in business, the one non-SK sector is ORD-SFO in UA DOM First, which should be par for the course, and I'll get quite a few bonus miles on Eurobonus. As I don't really need the points or sectors to maintain top level elite status i checked alternatives.

When toying around checking alternatives I found a very nice routing at a similar price: OSL-LHR-ORD-SFO-LHR-OSL with LHR-ORD and ORD-SFO in First, LHR-ORD on BA and ORD-SFO obviously on AA. The rest of the sectors in CW/CE. As I have to add a r/t domestic flight BA is a bit more expensive, of course, but as I have never travellled in First on any intercontinental flight, this certainly looked like a splurge to make, and having the F westbound also made sense to enjoy the product (I'll probably sleep well enough in CW).

So far so good: NOK 25000 with one TA leg in BA F, the other in CW. Then I checked on restrcted First, and found travelling both TAs in BA First costs around NOK 5000 extra (i.e. around NOK 30.000 in total). One leg in BA F and the other one in AA F fits in nicely between those two at NOK 27.500 or thereabouts.

Now for my questions: as I have never travelled First, I would like to get the full experience, and with BA obviously including the Concorde Room. At the same time, I do want to avoid unecessary extra domestic sectors in the US.

If I plan the least expensive variant (BA F out, BA CW home) is one sector in F enough to savour the F experience? Is the nighttime return on the 19.25 SFO-LHR worth the extra NOK 5000 (I sleep well in business on SK)?

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?

Sorry for probably being naïve, but I do come from the dark side!