I've been to USO facilities around the world and completely agree the volunteers are always great!!

Some of my experiences -

ATL - decent sized facility and gets a lot of traffic given contract flights in/out for R&R and deploying troops. Always a variety of snacks and beverages.

LAX - while not "near" anything, it's been great to my military family members and I. The also let eligible visitors park for free. This is usually where my family waits when I'm coming in from wherever.

Bagram - the Pat Tillman USO was always a refuge going in or out. Cold water, popcorn, and movies.

For deployed troops, the "USO in a box" program is great!

Stuttgart - provides a lot of info on Germany and other services.