I do not fly through EWR (if I can help it) but as I started to do more domestic travel last year, based on input from some friends and looking at the other benefits, I got myself an AMEX Platinum card. At SFO and LAS I am able to use the Centurion lounge which I really like. In SAN I am able to use the Airspace lounge. In LAX I am able to use the AS lounge. At LHR if I was not in Polaris, or arrive after 12 noon, I use the Priority Pass lounge which is right next door to the United Arrivals lounge for a shower. The AMEX card also gives me $15 or uber each month and pays for my GE, and much to my surprise gives me gold status with Hilton. I liked the new Polaris lounge at SFO but am not a huge fan of UCs.