I find 2 things work, 1st I don't let them find the remote, their is a lot of things they can do for fun with out the TV and they have less of a tendency to spend all there time watching it.
2nd when it starts getting late and they are all exhausted I send them to bed then don't load the families till its morning in the game. I was having a big problem with them being exhausted till I did this now they are all fine most of the day time.
I play more at night because I work during the day so I have day/night switched but when i load the families they are all happy and have at least 3/4th of a bar full of energy. Just make sure you stock the fridge well or they will get weak.