Dr Pepper - I was at the upper elwha this summer. You have camping and river access about 2 miles down the main trail and off down a steep canyon trail. It gets hit pretty hard - because it is the first section you can get to, and the only section you can get to for any 1 day fishing trips.
The next river access is about 12 to 13 miles in. Fishing is OK here, but you really need to go to the 15 to 20+ mile stretch to find trout mecha. Mid week trips would be best - weekends do produce a bit of traffic up there.
To help make the trip successful, plan the trip when the river level is very low (to increase your chances of finding a crossing point, and those less pressured stretches) - wading can be tricky in this fast moving river. In some places, if you fall in, you dissapear into a dark canyon full of nasty white water. Bring light waders and wading boots (the water is COLD) and plan to fish the holes just off the beaten path.
Wear GOOD hiking boots, and expect a few blisters (bring blister protection like mole skin - duct tape works too...).
You can't target dollies/bull trout, but they are there - and hit most bait fish / crawfish / leech imitators - as will the wild rainbows. You won't see many (or any) if you just fish nymphs and Dry flies.
You must use single barbles hooks on your flies, spoons, and spinners. NO BAIT. And you can keep a couple for the frying pan - but 1 14inch fish is probably all you'll need for dinner - if you insist on eating fish... Carefully release all others.