I didn't realize you were so close! (ha), but am with you on the decision to go now, and to hike the AT.
I haven't picked the actual last day, but it'll be first week in August for me. Similar to some of your thoughts on what will happen after you leave and the fact that it will not be your problem I have those thoughts as well. Coworker (subordinate) was unprofessional at a hearing yesterday, and complaining afterwards about the proceedings. Came back to the office and used the word "sucked" about the meeting to our CEO. I want to have a talk with her today, but nah...maybe not.
Anyway, I'll be heading NOBO in mid August and wave as I go by. I'll be on the BMW with two wheels over on the Blue Ridge Parkway (or Skyline Drive depending on how far south you'll be in late August).
I've enjoyed reading your words and can identify with you.
Great job! Now go have some fun!!!