I've stayed at both Kalaloch Lodge (right on the beach) and at Lake Quinault Lodge (on a lake in the middle of the forest.) Both were fantastic. If you can split your stay between the two, I'd recommend that. Kalaloch Lodge has a hotel and a bunch of individual cabins (with kitchens and fireplaces), all on a bluff overlooking the Pacific with miles and miles of empty beach to walk on. Lake Quinault Lodge is a wonderful older lodge on a lake in the middle of the rain forest, also with lots of nearby trails. Here's a link to your options within and near the park:

http://www.nationalparkreservations....FQpvbAodKUOl_w