Given the possibility of time travel I can think of a number of vintage seasons* I wouldn't mind visiting.
1. 8 October 1829 - Rainhill, England to watch The Rocket get put through her paces.
2. Trackside on the Boston & Maine in 1848 to watch the Antelope blow past at 60 mph.
3. Any day in 1864 at Alexandria, Virginia so I could just walk around the USMRR shop complex.
4. 1 A.M. on the morning of 3 May 1867 - at the east facing of Summit tunnel when the tunneling crews broke through.
5. From dawn to dusk 27 April 1869 on the Central Pacific mainline to watch Crocker's men lay over 10 miles of track.
6. Anywhere trackside on the IC on that weekend in 1886 when the gandydancers re-gauged the entire system.
7. Trackside anywhere on the stretch of NYC track where 999 was turned loose and allowed to roll.
9. Safely covered in mud and water in the western half of Skunk Lake on 1 September 1894 to watch (and possibly offer assistance to) Porter John Blair and the other crew members of the Limited, Train #4 roll to a stop and get their charges into the water and safely away from the Great Hinckley Fire.
...there are many others but these would be among my first choices.
*for those who remember the Kutter and Moore science fiction short story