dibbern2 - 12:45 am on Jan 9, 2011 (gmt 0)
Isle Royal NP, one of the most unusual and possibly wildest. Has its own wolf population. Its almost a full day boat ride to get to, or else float plane.
Don't overlook the Virgin Islands. Buck Island off St Croix is one of the most beautiful beaches in the world, and no resorts or other commercial development! Not sure its a NP, might be a National Something else.