Regarding lounge access with the Amex/Priority Pass card, I have never had to pay the guest fee for my spouse, in SXM, the US, or Canada. I'm not sure if we get a different benefit in Canada but this is what it says on the Canadian Amex site:

Priority Pass
Simply relax and unwind in any of the 700 Priority Pass lounges around the world. Simply present your Priority Pass membership card (which you will receive after you enroll) and a ticket valid for travel on that day on any airline, regardless of class of service. If you’re travelling with a guest, he or she may accompany you free of charge. For each additional guest, a nominal fee of $27 USD per person per visit will be charged to your Platinum Card.