Then go with Bear Mountain. R-Day is long--by the time they take the Oath and complete the march into Washington Hall and those big wooden doors slam shut...and then you get back to your car...you may not wish to drive after being up to drop your kid off at Zero Dark Thirty and then walking about in the sun all day.
Also, you will want to make a plan for your kid to eat something that morning before the early drop off. Sometimes the different hotels will have a super early breakfast. Otherwise, pack bars and a couple bottles of water. Being close is key because your kid could be in the 0600 drop off group.