7 is a good age. Willing to 'help'... and still coming up with those zingers that amaze you.
I know it's cliche to say but I believe it's true.... grandkids are more enjoyable to be around than your own kids were.
With your own kids your always having to be <shudder> a parent. Making rules, enforcing rules, but when a grandparent it's mostly 'rules are made to be broken'.