Just to clear up the many wrong answers in this thread.

Business/First is only good for PC access when you are traveling internationally. EWRLAX would not qualify.

If you have ANY international BF segment in your itinerary you will have access to ALL PCs along that itinerary no matter what date or class or service the additional segments are. Same day only refers to Sky Team or International First (IAHCZM). BTW International BF entitles the passenger to 2 guests....IF none.

AMEX Platinum rules are 2 guests OR spouse and children under 21.

AMEX extra guests are $25 to use one club or $45 to use ALL clubs. For example if you were going FLL-IAH-LAX-GUM you could pay the $45 and use 4 PCs.

Where the idea that AMEX pays CO $16 per visitor came from I don't know but it's not even close. Think single digits on this one.