I think they all are older. The modern repros have a concave bottom and stiples around the perimeter. The dates (two digits) should be on the sides of each bottle near where they bow out. The reason "Wash" is smaller is to fit the long city name above or it may have been made by a different glass company.
Christmas cokes were issued from circa 1923 to 1938 so you have to look at the date on the side to see the actual bottle date.
Scuba, I would grab those cokes you find. Put 'em in wooden 24-cases and the antique gas station crowd buys them for display. I get $50 or so for them in my neck of the woods, even if some of the bottles are repros.
I wish I was finding some Cokes, I'm on a dry spell.