We have visited a number of Oregon Trail sites in Nebraska and Wyoming. The following are links in an east to west sequence.
Fort Kearney - Just off I80 in Kearney NB
Ash Hollow State Park On route 26 west of Ogalalla. There are two locations there. The first on the left side is Windlass Hill. A nice trail to the top of the hill with interpretive signs and good views from the top.
Courthouse Rock and Jail Rock can be seen in the distance from route 26 shortly before you get to -
Chimney Rock A very nice visitor center there.
Scotts BluffFort Laramie Historic Site, a major stop on the Trail. Some of the original buildings have been reconstructed.
Oregon Trail Ruts at Guernsey WY. The best preserved ruts along the Trail. Get off the paved loop trail and follow the down the ruts to see more ruts. A neat feeling to walk where the immigrants walked 150 years ago.

Register Cliff Only about 2 miles from the ruts and many names still visible.
Take I25 to Casper and then route 220 to
Independence Rock where many immigrants carved their names in the rock.
Just a mile or two further is
Devils Gate.Another landmark on the Trail is
Split Rock, which is visible from Route 287.
Route 28 between Lander and Farson WY is the
South Pass, where the immigrants crossed the continental divide.
That's as far west as we have gone on the Trail. So much to see, so little time.