I have a 4 hour 20 minute layover in Narita this Saturday (connecting from the US to Beijing). I doubt that this is enough time to leave the airport - agree?

Is there a gym in the airport? What about at a nearby hotel?

Lots of Narita airport info here:

http://www.narita-airport.jp/en/

I don't think Narita airport has a gym. As for nearby hotels, try Radisson (looks like non-guests use ok), ANA hotel and Hilton (looks like only for guests).

HOWEVER, by the time you go through the passport control and customs, get the shuttle bus to/from the airport, you probably have an hour or so at most. Alternative is to use their shower/day-use room airside, get massage, or have some Japanese food on the landside.

I would not leave Narita with a 4 hr layover. No way.

with only 4 hours you can not leave the airport really....it can take almost an hour sometimes to go through immigration