SFO. BART takes a little longer but it's a great city. Similarly, MARTA from ATL is a long ride.

SAN has a street car but it doesn't seem to go to the historic downtown area. I'm not sure whether it can take you near the zoo.

DCA is great, especially if your destination doesn't require a transfer. However, you can't get to Georgetown easily.

PHL has a train to University City and Center City, but it doesn't go to Society Hill.

KUL has train service.

VIE has a new train.

FRA has two train stations in the airport, local and long distance. In addition to Frankfurt, which isn't a very interesting city, you can go often and quickly to Mainz or Wiesbaden.

HND has a monorail and another light rail system, but it's not so good for interesting areas of
Tokyo; you need to transfer to the subway.

LHR has the tube, cheap to central London but it takes a long time. The LGW express train is expensive.

PVG has the Maglev, which is fun to try but it's an expensive ride to an uninteresting part of Shanghai. There's also a long and crowded subway line.

ICN now has a subway or light rail line to downtown Seoul, although it's a long distance.

IIRT KIX has rail service to both Kyoto and Osaka, although the quick line doesn't go to the center of Osaka or near things for tourists. In Kyoto, many of the interesting things to do aren't in the center.

Also, as mentioned above, SEA, PDX, MSP, MDW (ORD is like CDG in that the transportation takes a long time), MSP, BOS, SIN, AMS.