It very much depends on your aims for the holiday, are you mixing aeroplanes with leisure /sightseeing?
San Diego is a wonderful place to visit with its harbour & beaches. As mentioned above, the Museum there is very good, but not huge. There is also a collection on a Carrier. You could spend an hour or so at Coronado Beach and watch the US Navy in operation from North Island.
March AFB further North has a very good Museum too.
Most Bases have a nice collection of Gate guards which are often easy to see, as in HaveQuick's post #3.
Boeing Field in Seattle is also recommended, as is the Carrier in New York.
2 most excellent Museums are The US Navy Museum at Pensacola, Fl, and the US Army Museum at Fort Rucker, Al. However (according to conversations on "Fighter Control" website) you need to pre-book your visits and this is a bit hit and miss.