I would recommend not overplanning and trying to find things to add. a first trip is the baseline for any future trip and there is such a thing as setting the bar too high. Your going to show him around and why you love the place, he'll have a ball. take him to a few of your favorite spots to eat.. It's easy to overwhelm someone that has never been. running around like a chicken with your head off is not many peoples idea of a vacation..
As far as what to do to pass the time. I think at some point you need to turn away from the planning. I personally find it helps when you get back because the trip doesn't blur into the plan so you take a break, do the vacation and get home to work.. I find the other way you plan, do it but it doesn't really feel like you went and then you get home anxious to get to your vacation but you just did it..
Did you get the new shoes yet? are you ready to walk 7-15 miles per day? walk around the neighborhood adding a little more every day, break in the new shoes now and get through the pain and build up your muscles before you get there.