I recently wrote about 4-year-olds, and why they're so awesome. No longer toddlers, but not yet "big kids", they still snuggle like the baby you miss, but have enough independence that they're fun to hang out with.
Not to dis on the 5-year-olds, but SIX is an amazing age. I learned this when our oldest child's first grade teacher turned me on to a classic, fabulous book about early childhood development -- with an educational focus. It's a little technical and geeky, but if you like this stuff you'll LOVE this book. The upshot is this: Something magical happens in first grade. At some point during the year, each kid will go through an amazing transformation. She'll start out like a kindergartener -- still a little clingy and whiny, and living in the magic world of imagination -- ponies, princesses, and fairies. But she'll end up the year like a KID -- an honest-to-goodness Grade School Kid -- who can be swayed by logic, her peers, and the rules of the world.
Schools in many European countries understand this developmental fact, and that's why they don't do serious academic work until age 7. But their outcomes are much better than ours -- because they're working WITH development, not AGAINST it. You can use this to your advantage by not falling for the ubiquitous pressure to force younger and younger children to do "academics". Having realistic expectations for the behavior and learning of your preschooler and kindergartener will potentially save you a lot of worry when you're told they're not performing up to "standards". The "standards" of most school systems weren't created with normal development in mind. But that's another big topic for another day.
Dr. Heather The BabyShrink Mom of Four, Parenting Expert