If you mainly fly international on AF/KL, maybe you would want to pay for a Delta SkyClubs membership because it has reciprocity at KLM lounges in Amsterdam and I believe may provide reciprocal access to some AF lounges-- I haven't test tested AF recently because I have been ST E+ for a number of years, so it might be good to research AF lounge accessibility. In any case, it sounds like the lounges you want to use most are the AF/KL ones that are simply not accessible through credit card memberships. Thus, my idea is that a U.S. lounge membership purchased from a Skyteam carrier may be better for your needs. By the way, if you use KL alot, it might be worth checking with them, as I think they had some type of purchaseable status (at least at one time) that provided lounge access in AMS. Let us know if you find an interesting credit card lounge combination that meets your needs.