Roppongi Hills is a building complex that caters all your needs, from lodging to restaurants and entertainment. The main tower, Mori Tower, is one of the tallest skyscraper in the city and offers a fantastic view of Tokyo from the observation deck.
I wanted to go to Kyoto tower in the evening in the hope to get a nice view of the city by night but I was unfortunately 4 minutes late to buy my ticket. (Closed at 9:30 I think!). I ended up walking around the tower and the train station, Kyoto-Yodobashi.