For a nice day trip from Gig Harbor, I would highly recommend driving west on WA-302 to Belfair, then south on WA-106 along the Hood Canal, linking up with US-101 near Hoodsport. You can make a loop by heading north, crossing the Hood Canal Bridge and back down through Bremerton. Easy drive with fabulous scenery, especially if it’s a rare clear day. Plenty of cool spots to stop on the way (Alderbrook Lodge, state parks, restaurants, etc.).