I've been to Tokyo a number of times... don't worry about navigating the subway system. Many stations and ticket machines have English, and even when they don't it's not hard to figure out. Just be aware that there is more than one underground train network with separate ticketing systems.
Get a "map of tokyo" from a hotel. I usually stay at the Hotel Okura (near Toranomon station), but like the maps that the Prince hotels provide. There is a Prince hotel (the "Tokyo Prince") right near Tokyo Tower. There are also three of them (the Takanawa Prince, New Takanawa Prince, and Takanawa Prince Hotel Sakura) just north of Shinagawa station, about a half mile up the hill across from the station). Get thee a map!
Taxis are expensive. If you want to take one, don't open or close the rear door to get in/out. You will offend the driver and show your ignorance. He can open and close it from the front seat. My suggestion: subways. Crowded at times, but cheap and quick.
Also... the Akihabara area is fun, but you really won't get much of a bargain on anything usable in the States. Just the facts. If you are considering purchasing something like a digital camera or camcorder, do ALL your homework here... get model numbers and prices. Then, shop for it in Tokyo. You might find a better price, but you probably won't.
One last fun culture note: Kindly accept the little packs of tissue people may offer you on the street. No, you can't read the advertising on them, but their utility/purpose will become clear when you discover that public toilets typically do not have paper.
EDR
[This message has been edited by erobbins (edited 12 November 2001).]