We (two couples) utilized the Dome car and optional bus tour and it was well worth it. From check-in, the train, and entertainment the staff were all exceptionally nice.
Entertainment: skit before boarding, a guitar player, fiddle player, Marshall, train robbers were all talented.
Buffet selections were fresh, and plentiful. The three bus stops, in Grand Canyon, left a 1/2 hr. viewing and were informative.
This was taken on our second day visiting GC. It does not, given it is a slow ride to the canyon, allow you anytime to spend on your own visiting the canyon.