I've been thinking about this a lot. I've got the Amex Gold and have racked up quite a lot of points but I feel I'd get more benefit from other cards. I was thinking of going with some combo of Hilton and Marriott cards as that's where most of our stays are. Then I could get free breakfast most of the time and work towards some free hotel stays. Flying non-rev, I don't see any benefit with the Amex Platinam and other cards that offer Priority Pass are useless as the lounges are not in the UA terminals.

Personally I feel that if I've got time to go to the lounge, then I'm arriving at the airport too early and if I need access, I can just buy it at the airport.

I might start with the Hilton Surpass card as it covers most of my major spending categories.