I'm sure Narita will get old after 23 hours. Visit a new part of Tokyo! It's only an hour's train ride away and there's so much to see. What's your exact timing?

If you've only been around Asakusa, I would pay a visit to Ginza, Tsukiji, Shiodome and that part of town, which is all within walking distance of Tokyo Station if you have good legs. It's a good composite of the old and contemporary Japan, I think, and there are many good and so-so hotels in that area where you can stay.

Going from Tokyo Tower to Roppongi Hills through Azabu-Juban is also a nice walking tour of the ritzier part of Tokyo (you'll probably bump into some American investment bankers' families en route), and there are plenty of neat shops and eateries along the way...