As an AF veteran...

...I hope to use either the perimeter of an airbase or a Cold War museum as a background on my (forever) planned layout. The base could justify a spur traveled by a freelanced switcher and the museum could be served by light rail transit. Not to mention the museum exterior that would invite modeling tanks, missiles, etc.

Agreed! Air Base or museum would offer many possibilities

Air bases and other military installations often have military hardware displayed at the gate, including aircraft in parked position or up on stands.  Even just a corner of an air base in the background of a layout could feature a fence, gate guardpost, a plane or two on display, and even a large sign for atmosphere - something like "Pardon our noise - It's the sound of freedom!"  If you happen to include background sounds, a nice effect could probably be the occasional roar of a plane taking off (jet or prop, depending on the era you model). 

In using the base itself to generate traffic, I read a history of Loring AFB in northern Maine receiving frequent rail deliveries of jet fuel in tank cars and coal in open hoppers (to fire the many boilers it must have taken to keep a sprawling base warm during a Maine winter!)

Rog

Nice idea

An airbase or air museum is a great idea.  As was mentioned, it can generate traffic, including the occasional special load with parts of a plane on a flatcar.  A base (any branch) can receive any sort of car imaginable, depending on the era.  Some army bases had their own narrow gauge lines, and you might have an interchange point there.

Depending on space and desire, you might even model a small part of the work area of the base, where trains would load and unload, for switching.  The entry to the base is a key point, and could throw a monkey wrench into a schedule--as the local freight arrives, the base is on alert, and the train has to drop off the cars on the way back.

If you like the more unusual rolling stock, then bases or airports justify ALL SORTS of neat stuf...

Northern AFBs

An interesting feature to model would be related to the heating system and could be done without the actual plant. I was stationed at Plattsburgh AFB in 1981 - 1982. The buildings there were heated by a massive steam distribution system that ran all over the base. Those pipes ran mostly above ground due to the deep frost line but had to loop underground at streets and driveways.

http://www.historicmapworks.com/Buildings/preview.php?img=Images/NY/NY1864-199109pr.jpg&m=934343