Best Area to Stay in Tokyo?

Where do you think is the best area to stay in Tokyo for first-time travelers? Here is a post from a member of Japan Travel forum. "We are planning on visiting Tokyo Japan in the spring of 2009. What area would you recommend first time visitors to stay? We would like to visit the Fish Market, Disneyland, the shopping malls, and an onsen when we go. We are traveling with children ages 5 and 2..."
Any Suggestions?
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