Near the subway stations, there is the Kaminarimon, which is a large gate you have to see to understand.  Just a few moments down the walkway is a large temple where events are sometimes held.  Along the previously mentioned walk-way are many shops hawking their tourist wares during the daytime.  This varies from tack to traditional, but there is almost something for everyone.  There are a number of food stands open in the early evening near the vicinity of the temple, serving Yakisoba and other traditional foods, as well as beer and other drinks.

It you make the walk to Senzoku Street, you will find many small Izakaya restaurants and similar establishments.  Asakusa also has many "Snack" bars, which primarily cater to the middle-aged residence there.  

Every year, a number of festivals are held in Asakusa, including the Sumida River fireworks.

Asakusa isn't on the Yamanote Line (or any other JR line), but you can take Ginza Subway line from Ueno to get there.  (Several other routes are possible as well).