On my most recent trip to Japan, Esther, her husband, and I stayed at the Conrad Tokyo for 2 nights, which I booked using the 2 free weekend night certificates from the signup bonus of the Citi Hilton Reserve card. Given the points rate of 95,000 HHonors points per night or the cash rate of ~¥100,000 a night during cherry blossom season, this was a great deal!
The Conrad is right at the Shiodome Tokyo Metro stop. If you have a JR Pass and don’t want to pay extra to take the subway, you can go to the JR Shinbashi station and take a short 5-8 minute walk on either the overhead sky bridges, or through several underground plazas. I recommend the overhead sky bridges, which you can access from the Karasumori exit, as they are less complicated and faster due to less staircases and people.