Cold Harbor is well worth the stop...when I went there with a couple of gaming buddies we lucked out and got a personalized tour from one of the staff.
As mentioned not too much to see with a lot of the Peninsula fields...many have been built over, or its just an open field. Not much to Gaines's Mill, etc. I particularly found Malvern Hill a let down. There are plenty of little sites though...
However, just south of Petersburg is Pamplin Park -
http://www.pamplinpark.org/ - excellent grounds owned by one family since the Civil War before being released to the foundation to open the park...site of the final Union breakthrough of the siege. Also an excellent museum...very much worth your time, and not nearly as congested as the Manassas area.
If you do go North a driving tour of Fredericksburg/Chancellorsville/Wilderness/Spotsylvania is well worth it.
I live south of Richmond, but not sure what my availability will be during that time...already have a bit on the books, so we'll see.
LGen. Hamilton
II Corps
ANV, CSA