For DD2, I think I'll do something related to winter and the solstice since her birthday falls on the solstice most years. The day she was born was very snowy, so I'd like to incorporate that as well.
I really don't know what to put on DD1s crown. She missed Christmas, but was born before new years. She came home from the hospital on New Years Eve and that's when we really started our lives together.
I really want each child's birthday crown to be different, but it's so hard seeing that they're so close.