The Toden Arakawa Line, which originated in 1913, is one of only two remaining streetcars in Tokyo. It operates from Waseda Station in Shinjuku Ward, cutting through Toshima Ward and Kita Ward; before terminating at Minowabashi Station in Arakawa Ward.
On most of the 12 kilometer journey it runs along its own tracks; but it also runs along Meiji Dori between Asukayama Station and Oji Eki-mae Station. The entire ride takes about 50 minutes. It is a slow, and leisurely ride through some interesting sections of Tokyo's 'Shita-machi' (the traditional 'downtown').
Some interesting stations for explorations include:*Waseda - home of Waseda University, one of the top private universities in Japan. The campus is open to the public and is covered with many trees.
*Zoshigaya - Zoshigaya Cemetery and Gokokuji Temple
*Koshinzuka - Sugamo, the 'Harajuku' of the elderly
*Asukayama - Asukayama Park and it's museums
*Arakawa-yuenchimae - Children's amusement park
*Minowabashi - very 'downtown' atmosphere with once popular shotengai covered shopping arcade
A ride along the Arakawa Line costs a flat 160 yen, no matter how far you go. I recommend buying the 'Ichinichi Josya Ken' for 400 yen. With this ticket, you can hop on and off the train as much as you like for one day.
To see a map of the streetcar (with connecting train lines), use this link:
Exploring along the Arakawa Line is a great, inexpensive way to spend the day!
Shioiri Park has all the basics: baseball fields, tennis courts, large grassy lawns, picnic & BBQ areas, and an excellent playground. Located along the Sumida River, there is also a lovely cycling course. I was also impressed that although the riversides are concrete, they left a nice section of reeds right at the waters' edge.
I was surprised by, a huge, beautiful, traditional-style building that sits between the park and the Tokyo Metropolitan College of Industrial Technology. It is actually the 'Shirahige Nishi Pump Place', a water treatment facility. What a way to hide an unsightly necessity! (It is the large building on the left below).
Minami-Senju hosts a very large train freight depot. The Shioiri Park area lies just beside it, and the entire area, including all of the residences (mostly high-rise condos), are very new. I don't know what the area was before, but its 'renewal' is very impressive.
The park is not very large, but there are a lot of things for children to do. First, there are some rides including a small ferris wheel, merry-go-round, mini-train, and pedal-powered 'sky' cars.
Also in the park is an 'Animal Plaza'. In addition to some caged animals (monkeys, birds,...), there is a great petting zoo. Kids get a chance to get up close and personal with goats, deer, sheep, rabbits, and really cute guinea pigs! On a second visit to the park, the petting zoo was kept clean, but the waste in some of the other cages needed to be dealt with.
Many were enjoying a couple of small fishing ponds. This area was quite popular with older elementary school boys and their fathers. 
The park also contains some grassy picnic areas, some fast food outlets, and some great blow-up 'attractions'. There was also a live music performance the day I was there (traditional Japanese drumming, flutes,...).
If you just want to look around, the entrance fee is 200 yen for adults, 100 yen for children. For 1400 yen, and adult and child can enter together and they receive 12 tickets. Each ride 'costs' one ticket for a child, two tickets for an adult. Extra tickets can be purchased if necessary.