Dayton, OH is about equidistant from Columbus, OH and Cincinnati, OH, and since it's only an hour from each, the major metropolitan attractions one expects in a city are more likely to be found in one of the two outlying towns. The Air Force Museum is the exception. Dayton does have two interesting claims to fame, both related, both of which make it the ideal location for the U.S. Air Force Museum: it's the hometown of the Wright Brothers, who pioneered heavier-than-air flight, and it's the location of Wright-Patterson Air Force Base, one of America's largest military bases.
Dayton sits at the intersection of I-70 and I-75 in Ohio; Ohio exit 44A on I-70 will put you on Dayton's "beltway", I-675. Exit 15 on I-675 will drop you practically right on top of the museum: follow the brown signs.
Why it rocks
In terms of square feet and number of exhibits, it's larger than the National Air and Space Museum. It features actual airframes of many famous and obscure aircraft, with walkaround and walk-through exhibits of some of the larger aircraft. It's one of the few places a civilian can go to see an F-117, and currently the only place (to my knowledge) that an F-22 is on public static display. All manner of aircraft, from triplanes to experimental hypersonic vehicles, are on display. Most are former USAF military planes, but several are non-military. I can practically give the tour at National Air and Space Museum (which is not to diminish its coolness; I've just been there 20 or so times) but the USAFM still fascinates me every time I go.
There is a hall with the portraits and citations for every Medal of Honor winner--most of them posthumous--from the USAF and Army Air Corps in history; every time I visit, I like to read five or ten to remember that the uniform I wear to work every day is more than just a funny-looking blue polyester outfit.
There's an IMAX theater for those of you so inclined, and also the ubiquitous gift shop and cafeteria--purveyors of fine astronaut ice cream! If you're in Dayton for only one day, skip them and spend more time wandering around the aircraft displays. Don't miss the on-base annex which includes a bunch of planes you simply can't see anywhere else--for example, almost every plane to ever bear the designation Air Force One--most of which are available for you to walk through or around, depending on their size and condition.
What's the damage?
Your precious time--plan to spend the bulk of a day if you want to see most of the exhibits. On any day of the year except Thanksgiving, Christmas, and New Year's Day, anyone may walk in and view the museum for free.
In their words
All of this would be unavailable to the public without the efforts of the people who run the museum. Their mission statement goes like this:
The USAF Museum (USAFM) portrays the history and traditions of the United States Air Force through specialized displays and exhibition of historical items at the USAFM.
The museum manages the worldwide USAF Museum System (USAFMS) for museums and historical property, maintaining accountability for all USAF historical property. It is the focal point for all museum matters within the USAF, to include foreign and domestic, military and civilian museums.
The museum identifies, searches for, acquires, preserves, refurbishes, displays or stores, and manages items of historical or technological significance to the USAF.
The museum provides professional guidance and assistance to participants in the USAFMS, specifically the base level museums and displays/exhibits.
The museum manages the loan program for USAF historical property made available to non-USAF museums under the provisions of Public Law 10USC 2572.
The museum manages the historical property exchange program.
Information courtesy of USAF Museum website, http://www.wpafb.af.mil/museum/