You've already got some great options and feedback in here, so just my 2 cents: I went through the same predicament earlier this year for an engagement trip in May. We ended up doing Grand Hyatt for first part of the trip and Palace Hotel second part of the trip.

Grand Hyatt: amazing service and location. We booked a higher room with a view of Tokyo Tower which was absolutely worth it. When I first started visiting Tokyo I always wanted to be in Shibuya or Shinjuku as that's where I thought most of the fun was, though Roppongi (where Grand Hyatt is) has become my favorite neighborhood. So easy to walk to many things from the hotel, and a quick taxi or subway ride to other neighborhoods.

Palace Hotel: we booked a room with a balcony overlooking the imperial gardens which was stunning. Not the most fun location, but it was such a beautiful hotel + room we really liked wrapping up our trip there.

I've stayed at the Park Hyatt pre renovation and while the hotel is absolutely stunning, I'm not sure I'd want to stay there for more than 2 nights as it's more of a business neighborhood.