Sanja Matsuri
 

Has anyone here been in Tokyo for the Sanja Matsuri? Any tips on the best way to experience this festival?

you need happi
 

If you want to carry the mikoshi,you need at least one acquaintance who lives there.There's a lot of neighborhood association and each of them has its own mikoshi,but membership is strictly required when you carry it.
They identify your menbership by its designated happi you are wearing ,so you need a friend who have it.