As far as children's ages go, I feel like we have reached a sweet spot.
Our oldest is 7 and our youngest is 2. They can all walk, talk, feed themselves and sleep through the night.
They are all young enough to still have that childlike innocence and wonder but old enough to be a little independent. They are all small enough to still fit in car seats, but big enough to buckle themselves in. They are old enough to keep themselves entertained with the toys we have, but naive enough not to realize what "stuff" they're missing.
They all go to bed between 6:30 and 7:00 each night and sleep until 6:00 or 6:30 every morning. They are big enough to get themselves dressed and young enough to still let me pick out their outfits each night. They don't need their meals spoon-fed to them or chopped into little pieces, but they also don't eat us out of house and home (yet!).
They feel secure enough to be away from us, yet still choose to be with us whenever possible. They know how to talk, but haven't mastered the art of talking back. They love to play with their friends, but we can still control who those friends are. We know exactly where they are at all times, what they eat, and even how their digestive systems are working (yuck!).
I know the days are coming when they will grow up and become independent young adults, and I will try to see the positive side of that when I get there.
But for now, I am so content with these little souls I have been blessed with that I wish I could freeze them at this stage forever :)