I found the Sensoji and the surrounding area in Asakusa to be very interesting, and if you walk a bit further (ok quite a bit further), the Edo Tokyo Museum is very good as well.
And one of the must-see would be the Tsujiki Fish Market and the food market distract around it. If you can be bothered getting up super early, go and see the tuna auction as well. Supposedly there is no subway at that time, so you'll need to probably jump on a taxi. See you in Tokyo (I am arriving on the 10th in the early morning).
