Here are a few that I have found and have been recommended:
Picture books and early chapter books for early elementary (probably through age 8):
Papa and the Pioneer Quilt (Jean van Leeuwen) mentions several places along the way.
Journey of a Pioneer (Patricia Murphy)
The Josefina Story Quilt (Eleanor Coerr)Older kids:
If You Traveled in a Covered Wagon, Ellen Levine (in print)
Oregon at Last, A. Rutgers van der Loeff
On the Oregon Trail, Wilma Pitchford Hayes
Children of the Covered Wagon, Mary Jane Carr
On to Oregon, Honore Morrow
Oregon Trail, Francis Parkman and Smuel Morision (older kids probably)
Also here's a Biography list I found:
I will update as we go through this!