Hey Dave,
I've been a few times and have really enjoyed it. Many of the stereotypical aspects of Japan disappeared as soon as I got there.
I normally go in and out through Narita airport, which is not particularly close to Tokyo (an hour's train ride). Just about everything you'll need is in English, so there shouldn't be any difficulties getting into town.
Hotels in Tokyo were nowhere near as small as I had been led to believe. I can personally recommend the Okura in Tokyo - their rooms are bigger than most US hotel rooms. There do seem to be local vs foreigner rates though, a little like India.
http://www.okura.com/tokyo/index.html
Navigating the public transport system became a little more difficult than expected, as most of the station names are written in hiragana/kanji. You've got no chance, so try for an English version of the maps at one of the information kiosks (worth it just for the outfits that the girls wear!).
Roppongi is a very entertaining area at night. I highly recommend a visit there, providing that you don't have small children in tow. It's a bit of an eye opening experience. I was most surprised by the almost complete 'ownership' of doorman jobs by Nigerian guys.
http://en.wikipedia.org/wiki/Roppongi
Akihabara is the Tokyo electronics district. I wouldn't miss it for the world. It's astounding. It's difficult to explain, so just make sure that you go down there for a look. Comic stores, fancy outfits, lots of advertising, etc. Lots of fun things down there.
http://www.akiba.or.jp/index_e.html
Socially, the Japanese are in my experience, rather racist toward white people. I can back this with a lot of personal experience and the experience of many other close friends, but it's not worth it. I would recommed however, that you learn one or two basic Japanese phrases which will indicate a politeness to them - I have always found that this will turn around any situation. A little effort goes a long way.
http://news.bbc.co.uk/1/hi/world/asia-pacific/4671687.stm
http://gojapan.about.com is quite handy. It should have just about everything you need.
I really love Japan, and have a job offer there that I am hoping to accept in a couple of years time. I studied their language for 5 and a half years, although I have forgotten plenty of it. I hope you like it too.
