Stay at a hotel in NRT City. I would not bother with the Raddison as although it is close to the airport you then have to rely on a shuttle/taxi to get into Narita itself. Getting into Narita is a piece of cake. Some hotels offer shuttles but taking the JR is very easy to do.
I have stayed at the mercure a few times. It is around the corner from Narita station and a pretty good location, I think. There are also shops, restaurants,
etc very close by. Just down the block is a bus dept where you can take buses to various places.

Also, I'd recommend using left luggage at whatever NRT terminal will be flying from. I think rates start at about 500-600 yen depending on the size of the bag but if you leave your bags at the airport and take a small carry-on to your hotel you won't have to worry about dragging it around and off and on buses and trains.