Akasaka Prince Hotel
This is one of my favourite Chiristmas illuminaton.
When I was working (as a part time job) at Akasaka, I always took a look this hotel.
Staying this hostel is much expensive than Sakura Hostel, but you can enjoy this gorgeous illumination for free :)
To go there, just take Ginza line from Tawaramachi station and get off Akasakamitsuke station.
This area is also famous for night life but not so expensive like Roppongi area
and not so childish like Shibuya area.