The Amex Platinum card gives you access to NW Worldclubs and CO Presidents Clubs and there is no charge per visit. Diners have an extensive lounge program for most major non-North American airports, but not much in the U.S. or Canada. Priority Club is useful if you don't have appropriate status in oneworld or STAR, but the per visit charge makes it a costly alternative. U.S. airlines require separate club membership to access their domestic lounges, so elite status isn't much of a benefit (except for status and upgrades) in this regard.