I've got to welcome anyone with a nickname like that to FT, even if I am a bit late in doing so!

I think the Sakuragicho - Minato Mirai area is better than around Yokohama station. It might be dead after 10:30, I wouldn't know since I've never been there that late, but it is definitely more interesting during the day.

The Tokyu Toyoko line will get you to Shibuya on an express in about 30 minutes, if you want nightlife -- that should hold you up until the last express back at 12:03am.