I appreciate everyone's input. I'd definitely add a day to the trip if I had the time.
Honestly, it's more about covering the entire route in two days vs. touring and checking out the sights. Also, it's about getting in a somewhat substantial tour (at least for me) to see how I like it. I don't want to invest in camping gear, bags, stove and everything else needed for longer tours without first getting my feet wet.
Little Orleans looks like a good lunch stop for the first day, and Sharpsburg or Harper's Ferry for the second day. I'm really looking forward to the trip, and hope the weather cooperates.