A stroll by river is always nice. A run would be nicer (for me. heh)
If you are in Asakusa and visiting Sensoji, why not walk a little bit more and take in the view of Sumida River too?
There's usually a big crowd on the Azumabashi, a bridge with red railings. Come earlier, and you'd be able to see salarymen and office ladies hurrying over on the bridge to get to work.
The Tokyo Water Bus operates nearby too.
Walk down further and you'd be able to get this shot.
Stumble upon this.
Let your kid or kids blew off steam playing at a nearby playground, instead of staying glued to their games console
See boats pass by
Cross Azumabashi, walk through a park there (I forgot the name), and you can get this view of Tokyo Sky Tree.
Wish I can take a stroll there now. Sigh.