Have not, someday. You?
However, I HAVE walked the entire battlefield now twice over, about 8 days of hiking in all, just another benefit of my involvement in my son's Boy Scout career. I even earned the 5 part award for the effort, one of only a couple of awards a non-scout person can earn. Not that I care about the award, but I do have great interest in the battle and the war itself.
http://www.gettysburgscouting.org/trail.html
Little Round Top just seemed so small in scale to me. Devil's Den, exposed to fire from many sides. But walking Pickett's Charge is something everyone should do, it just deepens your understanding of the pivotal minutes of the war.
Gettysburg is one of my favorites. They have a nice ceremony on November 19 (anniversary of Lincoln's address) and then on the Saturday closest to the 19th they have a Remembrance Day parade. It's period troopers and bands.
I've walked across the field (Picketts). It's amazing how they all focused on the copse. After the Remembrance Day parade, they have a concert at Little Round Top. They have a period "band" playing period music. At sundown, they play taps. It's something looking out over the Devil's Den, etc. at sunset.
EDIT: My GGGrandfather was at Shiloh. He died on November 23, 1862 at Union Hospital #6 in Louisville, KY. He's buried at Cave Hill National Cemetery. I doubt any member of my family has ever been to his grave. It's on my bucket list.