I mostly stayed in the Asakusa area, which I really enjoyed. Everywhere else is just more or less an hour train ride away - Shinjuku, Shibuya, Ueno, Akihabara,etc. It's fun taking the subways and trains! Getting lost is part of the thrill of traveling! And finding food is never difficult. Even the cheap chicken at 7-11, Lawson, or Family Mart is very good! Just pair it with some salad.
Insider Tip:Cheap food? Just walk into any 7-11 or Lawson or Family Mart and take your pick. Or look for those small Japanese eateries with little "vending" machines right after the entrance. Pick what you like, pay for it, give the ticket to the staff, sit down, and wait for it to be served.