With some trepidation (because this may open up a whole 'nother debate) I add the following comment -

You mentioned that you have business to attend to in Kawasaki, Yokohama and Tokyo, so I've been wondering whether you might find it better to stay in Tokyo and commute down to Yokohama/Kawasaki. This would be quite feasible if you were to stay near Tokyo station (or near Shimbashi station or Shinagawa station .... ).

I can't really tell whether this will work for you, since I don't know what meetings you need to attend / what times etc. etc. But I can tell you that I sometimes make two or three trips from Tokyo to Yokohama/Kawasaki within one week and the travel isn't onerous at all.

Also, the trains from Narita to Tokyo take less time (and run more frequently) than trains from Narita to Yokohama - which might compensate for the "commute time" that you have to put in between Tokyo and Kawasaki.