Sheraton Miyako vs Westin Tokyo
Sheraton has a free bus service to shinagawa station, where you can catch the bullet train to Osaka.
Westin is not that far away either. Taxi is about 1500 yen.
It would take you more than 1.5 hours from nrt to Sheraton or Westin, why don't you just go to Osaka straight away then come back to Tokyo?