^ True. Lots of places (most places?) don't have it.
Before you choose a hotel, make sure it has convenient access to public transit and is not too far away from the places you want to go. A lot of the cheapest places to stay in the Tokyo area are in Narita: close to the airport, but FAR away from anything else. If you stay in Narita, you'll waste lots of time and money on trains.
It's very useful to know where you're going, especially if your time is limited. Detailed maps are key,
since Japanese addresses employ a bizarre* system that is virtually useless without a map. I swear by the
Tokyo City Atlas, which is my constant companion when I'm there. Before I go on my trip, I put little Post-It flags in the book, marking the various places I want to go.
* Bizarre to us Westerners, that is. It does have a certain logic to it, in its general-to-specific organization.
Anything specific you want to know? I've been to Tokyo five times (all short trips, one to two weeks each), so I will probably have some knowledge or opinions, or can at least point you in the right direction to get the information you seek.