Not sure of any evening shows but there are a lot of Tribute Acts in Kalamaki this year who between them are probably on most nights. You could take him to Ambrosia for dinner - great restaurant on the Strip. All of the waiters do Greek dancing and plate smashing etc. at around 9pm so would go for about 8-8:30. Kid will love it too! If you wait until a Sunday, Stani's restaurant has a Greek night but I would advise to maybe have a stroll along one day and book it in advance.....
Have to say though most bars in Kalamaki welcome kids and lots have things to keep them entertained (depending on ages).
Have a fab holiday - we arrive 29th :)
Edited: 4:09 pm, August 01, 2013