I have never seen a website that lists any class called "sightseeing seats". On china-diy-travel.com there are some trains on the Shanghai-Wuhan line with business class. Business class seats are not always "sightseeing" but VIP usually are.
Understand also that you can be in the first or last car. The first car (behind the driver) on a trip will be the last car on the returning trip. After arriving at destination, the employees turn the seats around and the train just goes in the opposite direction.
Even VIP seats may not have much of a view when the seats are turned around. I have a photo of such a situation but have no idea how to post it here.