Ooooh! I can't wait to see everyone else's answers to this. Let me throw out a few nominations to start with (completely from memory, and not checking the Tony list) and then see where it goes:
The contrasts through the whole journey. If you take it in the early Spring, as we did, you get to go from surfing in Southern California to snow in Oregon and rain in Washington. It's an amazing trip and, as the flagship of Amtrak, it's got an observation car, dining car, movie theater, kids playroom, etc.
Construction cranes do not need to be 300 meters in the air on an empty construction site. They only need to be at a given height above the highest floor being worked on. For most large buildings, construction cranes start at a relatively low height, and then are “jumped” up every few days or weeks as the superstructure is being constructed, continually being tied into the building every few floors: