The obvious to me is my home town with JFK - LGA - EWR (but EWR is in Jersey, so screw it).
San Francisco (sort of) SFO - OAK - SJC (you can see OAK from SFO and vise-versa).
London LHR - LGW - LCY - STN
Los Angeles (in a loose way) LAX - ONT - VNY - PMD (all are "Los Angeles World Airports")
Miami (again loosely) MIA - FLL
DC IAD - DCA - BWI
Paris CDG - ORY
Tokyo NRT - HND
I avoid flying anywhere else ..............
(no one really goes to Chicago, Houston, Seoul anyway why do they need more than one airport?)