I have used the Hilton Narita as a base for a weekend or three days, with one day spent in Narita town and one or two days in Tokyo. It's not too bad for a day trip into Tokyo, as long as you understand that a lot of time will be spent on the train. For one or two day trips to Tokyo, it is fine. For anything longer, staying in Tokyo is essential, in my opinion. Narita town is well worth seeing as it has an impressive temple and gardens, and the walk from the train station (where the bus from the Hilton drops you) to the temple and gardens is quite interesting and has many places to stop and have tea or shop.