The T3 Amex Centurion Lounge is perfectly nice but I can't imagine doing a bunch of security hassle for it given that anyone with CL access also has Priority Pass lounges in T5 + Plaza Premium T5 access from the same means by which you get T3 CL.

it's not like you're getting Krug, massages, your own butler, a private bathtub and made to order sit down restaurant dining over in the CL. This isn't some kind of "OMG TEH BEST LOUNGE EVARRRR" experience like the FCT in FRA, Al Safwa in DOH, CX Pier F in HKG or what have you. You're in a nice enough windowless room with no natural light or tarmac views with showers, a buffet and a bar. Food and drink's fine but it's certainly not destination dining.