Regarding US holidays...
...or North American holidays in general:
The east coast is home to all that is American...its heritage, its architecture, its informing landscape and, not surprisingly, its climate. JFK isn't the best portal to all of that, but its all we've got. To get to the North East I recommend QF all the way to Kennedy, then either ground + feeder to your destination or hire car. Distances are manageable easily.
I have ventured everywhere from the Arctic to Tiera Del Fuego ex New York with happy memories. Not so much out of LAX. I actually lived in the LAX neighbourhood for over a year, and retain industry contacts there still, so let that be your guide.
For me, the middle of North America is fly-over country, the east and the west sections are driving zones out of your gateway of choice. Kennedy is about as good as you can get from OZ. Dallas, and its sister hub at Chicago is as good as you can get for the middle, and LAX, sorry to say, rules the west coast.