You can drive all the way to the top if you just want a view of the dam. The hike up is decent from the visitor center but most of the view of the river below will be blocked by trees in the summer. The bluffs overlooking the trail are still a nice enough view to make up for it. I didn't even mind the vultures circling me like they knew something I didn't.
We completed the trail on a warm December Saturday and had the entire trail to ourselves. We parked at the Visitor's Center (which was closed for the season) and then walked up the road to the end and the nice overlook. I recommend this route as there is another nice overlook along the road that you would miss if you just hiked the trail out and back.
From the second overlook (and the end of the road), you descend several stairs and the trail leads back to the visitor's center. The trail is easy and was no problem for my family, including my energetic six year old boy. There are a couple short wooden bridges along the trail and plenty of views of the river and the dam.
The trail itself was very clean - I did not see a single piece of trash. The problem of people leaving things behind on trails seems to be a common problem.
We found signs for two more trails in the area - Josh Park Trail and Collins Creek Trail.
If you are with small children, be sure to head over to the fish hatchery and follow the road through the camping area. There is a nice little playground for the kids that is right next to Collins Creek with ample seating and shade for the adults.