Originally Posted by
abmj-jr
I suppose you could. But the Suica card is much more useful in and around Tokyo and also valid in Kyoto - and you can turn it in for a refund of remaining funds, less a small service fee, at the end of your trip. Suica will work anywhere the subway card will but the reverse is not true.
Right, the subway card works on ONE of the two subway lines, but not on the JR trains or the private surface commuter trains, and being unfamiliar with Tokyo, you cannot predict which forms of transport you will need. (I've lived in and have been traveling to Tokyo for forty years, and even I can't predict which forms of transport I will need during a stay.)
The Suica gives you maximum flexibility, since it is valid on all the forms of transportation that you are likely to use.