About the only idea I’d like to see is something like an engineering mode, where you can plan out and tweak an entire route before committing to build the project, and maybe then a system whereby the route takes time and resources to actually build.
I don’t bother suggesting it though, as I’m fairly sure not many people are going to care much for the idea, and I don’t think it’s likely the developers will ever go down that route.
Outside of that, I’m not particularly interested in additional vehicles or such. I would sooner they carried on fleshing out the existing game systems, filled out the map generation with more interesting features, and maybe worked in some new terrain types.
I’m not really concerned what they add, provided it enhances the game, so I like to talk over what I think will and won’t do that.
I’m interested in this particular topic as I actually think the idea of having international airports and shipping ports would be a great addition to the game, and I’d like to see a discussion develop over how best that might work (as implemented badly, it could be pretty boring and throwaway, while I feel it has the potential to be a really engaging and unique feature if it was handled well).