River Scene is an easy trail along the river with little elevation change and is pretty smooth. The path is pretty wide in parts and is a good way to get warmed up without riding on pavement. I like to use it to warm up before and cool down after rides.
Then main stretch on the west side of Keifer Creek Rd is usually done as an out and back. It also connects to Stinging Nettle trail to the west of the washout area between the railroad tracks and the river. If you keep an eye out on the edge of the trail there are also a few little jumps and bumps to keep the fun factor up a little.
On your way back out from the washout, keep right and you'll cross a field to the other section of River Scene. This section has a large deep sand trap that you may need to walk through, unless you are on a fat bike that is!
After the sand you'll cross the pavement and keep on the trail. keep an eye out to the left and you'll see short sections of trail that shoot out and around the old "Castle" train station foundations.
The trail will eventually take you back around to the train overpass on Kiefer Creek Rd.