My wife and I had a fantastic stay at FS Tokyo at Maranouchi at the end of August. Service was outstanding and perhaps the best we've had at any of the FS properties we've stayed at. A few of the employees mentioned the focus on service as the main selling point as the hotel lacks some of the breathtaking views other Tokyo hotels have (Aman, Park Hyatt, etc.) and the location is in a central business district. While all top hotels should be focused on service it was interesting they acknowledged the lack of views and semi-desirable location.
I highly recommend the Platform greeting/sending service if taking the train from Narita to Tokyo station. We declined it on arrival and that mistake turned a 5 minute walk into a 25 minute walk due to walking out the wrong exit in Tokyo station. Not fun in August heat and humidity. Upon leaving we probably could have figured it out however having a porter to carry the bags was refreshing. Location next to Tokyo station is convenient for exploring the city by train as well as taking the bullet train to cities outside of Tokyo.
Concierge was top notch and assisted with reservations at Narisawa, Ginza Sushi Ko, etc. Also went out of their way to assist with shipping some items back to the U.S. that wouldn't fit in the luggage.
Definitely lots of good options in Tokyo as we stopped at the Park Hyatt for a drink and did tea at the Aman. Both were impressive. The Four Seasons definitely held its own and the wife and I hope to return soon.