Most people might have figured this out sooner than I did, but the top floors and rooftops of department stores in Tokyo almost always feature an indoor/outdoor space to chill out up high, drink some coffee, read a book, smoke a cigarette, whatever. There are benches, plants, and usually a decent view.
This is from the 12th floor of Takashimaya Times Square on the South side of Shinjuku Station, overlooking Shinjuku Park. You can test your cred by picking out the distant landmarks of all the neighborhoods you've been drunk in. Or taken walks or something, whatever, I don't know what you sickos get up to.
One floor up is a patio space. The top three floors are all restaurants and cafes so you can grab a coffee, although after nearly 3 years in Japan I still make a face at paying $4 for a little cup of iced sludge.
I've always had a weird relationship with Shinjuku.