The observatory at Roppongi Hills (Tokyo City View) is one of Tokyo's most popular viewpoints, commanding an impressive view of the entire city. Ride up on a special elevator to the 52nd floor, and you will see Tokyo Tower right under your nose. Especially during the Christmas season, the night view from here is very pretty and colorful. And some Christmas events and live music concerts take place here during this season, as well.
Another great place to see beautiful illumination in Roppongi is Tokyo Midtown. Walk down Gaien-Higashi Street and go into the garden area. A tree-lined road with gorgeous light-up decoration leads you to Starlight Garden. Here, you can enjoy a spectacular 3-minute illumination show for free.