Obviously the highlight is the climb up the Front Range upon leaving Denver (right side), then winding through the canyons all day. Highlights include the Moffat Tunnel, Gore Canyon (left side), Glenwood Canyon (right side and around which you should pass #6) just before Glenwood Springs. That was where the Vista Dome Monument was on US 6, since moved to the museum in Golden. West of Grand Junction is Ruby Canyon, where the state line is marked on the canyon wall at Utaline (mark is on right side, although there are good views on both sides here). Then the run through the desert with the Book Cliffs off on the right side of the train.
The next morning you will go over Donner Pass. Viewing is good out of both sides, but the right side is a bit better generally, particularly after you exit Tunnel 41 at Norden, as you go along the ridge with a valley, I-80 and other peaks visible across the valley from the ridge.
As to onboard highlights, it is a standard-issue Western LD Superliner. Nothing particularly special about it.