While I agree that Tokyo Station can be a challenge to navigate, if you're in the underground shopping arcade or trying to find the train to Disneyland, finding the Tokyo Station Courtyard Marriott shouldn't be too hard. My map (the pocket-sized "Bilingual Atlas of Tokyo," published by Tokyo Chizu Publishing and available in English-language bookstores) tells me that your hotel is located a few blocks from the Yaesu South Exit.

The two sides of Tokyo Station are referred to as Marunouchi (northwest) and Yaesu (Yah-eh-soo) (southeast). As you get off your train, keep your eyes peeled for overhead signs pointing you to the Yaesu side. All directional signs are in English and Japanese, and recently, I've seen Chinese and Korean as well.

Once you're on the Yaesu side, look for the south exit. Go out and look for the street that runs between the Mizuho Bank and the Yaesu Book Center (as I recall, both have English signs).

Here's a simplified map:

http://www.marriott.co.jp/hotelwebsi.../tyogz_map.pdf