RCC has better shower amenities.
ANA lounge has better showers and food choices.
Non of the NRT lounges have comfortable "reclining" couches that I've found two weeks ago, maybe others may know.

As far as Narita for 10 hours, depending on the time of the year and availability, Narita airport runs day tours in the morning for a couple of hours to Narita City, some temples, and some shopping area near the airport (i took one of these about 2 years ago) . The price is reasonable but check to see if it is available before getting a transit/visitor's visa. 10 hours in NRT, you might WANT to leave the secure area and browse the Terminal Mall which has a lot of dining and shopping choices...