Just finished a trip to Tokyo and stayed at both Grand Hyatt and Andaz. Full disclosure, I'm a repeat visitor of Tokyo and have stayed in various locations in the city. I would prefer Grand Hyatt over Andaz for the following reasons:
- Roppongi is more suitable for tourists than Toranomon Hills. The food options at Roppongi Hills alone should be a deciding factor if you're a tourists here for food. You're ten minutes away from dozens and dozens of options, from ramen like Afuri and Ginza Kagari, to exclusive Michelin dining options in Roppongi and nearby areas. The art museums, shopping, etc also don't hurt. Easy walk to subway station.
- The rooms may not be the most modern looking, but they are certainly well designed and timeless. The overall layout design of the room is better here than at Andaz, with the closet next to your bed. Frette bedsheets are a game changer. Evening turndown with water bottles and glasses by the bed, and a bucket of ice was much needed after a day out in the city. Was a little shocked Andaz didn't offer that.
- Club lounge is comfortable, we enjoyed breakfast and pre-dinner drinks here.
- Concierge service was helpful with booking restaurants.

Super enjoyable stay, had a brief chat with a fellow Andaz guest who also has stayed in GH and we shared the same thoughts. Again, no shade at Andaz but Toranomon is a business district after all.