Sorry to disappoint, but speaking as a regular on this route I can tell you that CX251 is the worst flight out of the four dailies if you want to maximize your F experience. See
here why that is the case.
I urge you to move to the other three flights instead. CX253 would be your choice if this is your first time in CX F. HKG based crew, nose of a 744, daytime flight and two "full" meals (the second meal is a "refreshment", but it is more of a dinner, on the other flights you get b'fast instead). This flight usually has the lowest load in F as well.
I prefer row 1 in F as opposed to row 2 which is favoured by many here.