My wife and I did an Oregon coast trip a few years ago and our favorite thing was a sand rail tour in Florence (about an hour south of Newport). They take you out in these huge, custom built dune buggies and you just fly around the dunes (link below). I would recommend doing the 1 hour tour as the 1/2 hour tour just isn't long enough.

I would also suggest eating at Georgie's Beachside Grill in Newport. It's in a great location overlooking the water and the food is fantastic.

http://www.sandland.com/sandrail-tours/

http://www.hallmarkinns.com/newport/georgies/