We just came through there a couple of weeks ago, and we've been from Washington to California and back many times. The grades aren't anything to fret over if you have a well matched combination. Proper tow vehicle, and well maintained RV. There will be a LOT of semi trucks and commercial vehicles. Just match your speed to theirs and you will be fine.
Just pick a day when there's no snow or ice if possible. Fog and freezing fog can also be a problem.
Once you do it a few times, it get's to be pretty easy drive. Please post back after you make the trip.
This pass will qualify you for the Mountain Pass Merit Badge.