Thanks everyone for the answers.
I am currently on low classes (H,O)
The office is paying for the tickets and I don't mind paying extra for the higher class but because I am travelling with a colleague I don't know if I should...
Any chance that we will both be upgraded if only I have S fare?

Regarding keeping the status, I have a lot of travel scheduled and usually have options for Business but I think that keeping the status will be hard even when flying C, I might just try to get Gold for another year unless LY really surprises me...

I can get AA top status with 4 C flights to the US while with LY it doesn't even get me gold... really don't get it, with BA it's something like 2.5 if you plan it correctly...