This website allows you to create license plate labels. They are pretty authentic. You could put the plates under the month they were born and the title of the month could be placed on suitcases. You could title it:
"Where Our Journey Began"
"Birthday Explorers" . . .Where Will Your Journey Lead You?"
One more :
"Cruisin" Through Our Year With Birthdays. . . the months could be listed on different kinds of convertibles. Hope this helps