I've not run from the WL resort recently. I do know that the trail was in good condition and you end running most of your mileage in the Fort Wilderness Trailer Area. As with most "jogging paths" it is best to run in the AM before many guests are out and about. The Resort map lists the trail at 2.5 miles, but you have several options to increase of decrease the mileage based on what loop you take at Ft W. The trail is partly shady (but in saying that it is the most tree lined trail I know of on property.
Another Excellent run is the Boardwlk run. I have driven over there several time and told the guard I was coming to run. As long as I offered to park in the back of the lot, I have never received any gruff.