Pedantic nit: Ikebukuro is actually before Shinjuku, but most Shinjuku-bound N'EXes don't stop there. Ikebukuro is a good, cheap-by-Japanese-standards to place eat and drink yourself silly, but then again, you can do that pretty much anywhere in Tokyo. One thing to see if you go there is the Toyota showroom, complete with the infamous smell-o-tronic vibrating movie theater (free!).