I am getting the Amex platinum. From what I can see the priority pass which you get with Amex platinum allows you to take an additional guest without the guest fee. The supplementary card holder can do the same . I.e 4 adults in total.
( You cannot buy this from priority pass directly !!!)
Right now I have a Priority pass unlimited which costs me £259. If I am travelling alone its fine .But every time I take Mrs.Ukdoctor to the lounge (guest) it costs me £15..
she doesn't travel that often to need her PP but my guest fee is at least £150 a year.
Add on tier status on a range of hotels Hilton gold SPG /Marriot gold /eurostar lounge access and it should be cost effective .
I have contacted Priority pass and have cancelled my current subscription .