I can provide a bit of color on two hotels you mention.

I moved my regular hotel from the Westin to the Park Hyatt and have never felt the slightest urge to go back. People on this site knock the PH for the 12 minute walk to Shinjuku station (the hotel does have a regular free shuttle if you don't want to walk), but it's at least a 10 minute walk to Ebisu station from the Westin even using the moving walkways between Ebisu Garden Place entrance and the station.

The Westin is a good hotel and there are a reasonable number of restaurant choices at Ebisu Garden Place nearby. There are also a goodly number of restaurants in the basement of the building the Park Hyatt is in. But the Westin isn't a luxury hotel and the Park Hyatt is.

You can do better than the Westin in Tokyo. If you do stay at the PH, try to get a room with a view towards Mt Fuji. If you get a clear day, it's amazing.