Which would be the best JR Pass and Duration to purchase

Hi,
The pass gives very little value if you're just staying put in the same city. The 7 day pass makes more sense and a 14 day pass would not pay off.

For Tokyo, if you want to use a subway, you might consider a 2 or 3 day subway pass. You should consider taking a day trip from Tokyo as well - there are many good places - Nikko, Izu, Kamakura, Kusatsu, etc. You can save a ton with a Tokyo Wide Pass.

Good luck.