This is a big area with lots of stuff to do around here. You're right down the road from Williamsburg, Jamestown, and Yorktown...so there is all kinds of historical stuff to see.
Williamsburg also has Busch Gardens theme park which will be opening up sometime in March. Last year they let military in free...not sure if they will do the same for 2006.
Newport News is booming right now, with lots of new bars,restaurants, and stores opening up not to far from Ft. Eustis.
There is water everywhere, so when it warms up a bit (probably in April), people head to the beach or head out fishing.
The Outer Banks of NC are only a couple of hours away...so its a fun place to go on weekends.
Norfolk and Virginia Beach are just to the east of Eustis. Lots of good places to go on that side of town.
FYI, if you are from NYC, AirTran flies from Newport News to NY-LaGuardia for like $50 each way.
The down side is that traffic has become a real pain around here. The closer we get to summer, the worse it gets.