The "saver" amount of miles you need for a one-way trip to/froim NRT from anywhere in the mainland US is the same.

However, depending on availability, you often need to pay double (of the "saver" amount of miles) if you're not flexible enough, not booking at the right time, or trying to fly at too popular a time.

So it's impossible to predict how many miles ("saver" or double that) returning from NRT will cost at some later date. It's only possible to check now how much it costs for your specific date or range of acceptable dates (and if you like that, book it before it disappears).

Now, the thing to understand is that not all routings that can be redeemed with AA miles show up online at aa.com. So if you don't see something you can use online, call up AA (once they're not overloaded with the DFW weather problem rebookiings) and maybe they can put on a less-obvious routing on another partner airline (if that's acceptable to you) for the lower "saver" amount of miles.