I have been using ForeFlight for iPhone since it came out.

Worth all $70 and then some.

I can't answer your question if it has EVERY airport out there, but I am 99% sure it does. What is cool is when you are looking at an airport, there is a "Near" button that shows all nearby airports. Great for alternate planning.

Check here and ask the developers:

iPhone app for pilots with aviation weather, AFD, flight plan filing, METARs, TAFs and more

Both Ernst and Arrowhead are in there for sure as I just checked.

It is probably the one app the will keep me forever on the iPhone. The design, polish, and very thorough amount of info that it provides is amazing.