So, I'm off in 10 days...

Any advise on places to see?

I should be able to go anywhere in Japan, but I am having trouble deciding on where to go. I'm not familiar with any museums or cool places to check out historicaly yet. I'm still doing research on locals and such.

If you can, I'd advise you to take the JR line up to Tokyo, then hop on the Shinkansen and go to Kyoto for at least two days of your trip. Yokohama is a nice place, too, but not even Tokyo can compare with the sheer amount of ancient culture present in Kyoto. It's a magnificent city. If you have to stay in Yokohama (business trip?) then I'd suggest trying to get down to Kamakura for a day trip. The Daibutsu is down that way, and a few swordsmiths have their shops there, too. (See how I just tied this topic to swords? :p)

I'll leaf through my journals and photo albums and see if I can remember any other places to visit.