Most of you are probably aware that the US Army Museum at Fort Belvoir, VA opened on Veteran's Day. I paid a visit about a week later. I spent about 2 hours doing a quick run through to get a feel for what they had, but will be returning to focus on specific periods, such as the Spanish-American War and Philippine Insurrection, post-CW Army, and the Cold War (which is when I was serving).
The Museum is located on ground outside the gated areas, so access is very easy. At the moment, the Museum requires visitors get a timed ticket so as to control the number of people visiting. These tickets are free and can be acquired online.
The Museum is divided into several halls: Founding the Nation (Revolution, 1812); Preserving the National (Civil War); Nation Overseas (Spanish-American, Philippine Insurection, etc), Global War (WWI, WWII, Korea), Cold War (mostly on the Army in Germany); Changing World (Iraq, Afghanistan, etc); and Army and Society. There is also a Army Action Center (virtual experiences), Theater (being used for a retirement ceremony while I was there), Cafe, Museum, Experimental Learning Center, Medal of Honor Experience and Garden, Veteran's Hall, and special exhibits (Nisei Soldiers right now).
There is a small exhibit of the US Army during the Plains Wars. There is an infantryman and mounted Buffalo Soldier, along with a number of weapons and related equipment. I tried taking some photos but was defeated by the glare of several lights reflecting off the glass. I'll try again next visit.
All the exhibits focus on the US Army and the only foreign items are captured weapons, equipment and personal effects mostly brought home by veterans. I noted that there was actually very little on the Confederate Army, except one exhibit on West Point graduates who left the US Army to join the Confederacy.