Writing this post as a clearinghouse for ambient observations. Written from the perspective of a scrub who watches pro games sometimes.

Starcraft

Information can vary from extremely cheap to extremely expensive, but because of the simplicity of tech trees, much can be gleaned from seeing just one unit or one structure. At higher and higher levels, the metagame becomes more constraining and players get better about guarding their secrets, so information becomes much more expensive and much more valuable. Probably still my favourite RTS in terms of information economy. (at least in terms of the highly standardized map designs that pro players seem to expect.)

Supreme Commander/Zero-K

Information is pretty much always very cheap. Scout or spy planes are just cheap as hell, and if you spend enough you can get a total view of what your enemy is up to. Long unit travel times mean this cheap information gets more valuable on bigger and bigger maps, since you can just start building the counter as your opponent's strategy develops. Nukes are a great example of this: you should pretty much never get surprise nuked at a high level since if someone's building one, you should already know. (afaik, less confident about this assessment. there may also be exceptions depending on map design.)

Warzone 2100

I don't know what the fuck is going on here man. It seems like all the pros play on ultra-simplified, super high econ maps, which is fair, given the severe complexity of the tech tree and the worthlessness of information compared to its moderate expense — pursuing a specific tech branch does not really require a lot of commitment in the same way as Starcraft.

I spent a little while playing my buddy in 1v1s in this game on the stock maps and we would always kill one another in the super early game based on MG/flamer tank rush tactics. Games on stock maps have almost no stability. I doubt it would be possible to reach the end of the tech tree in even the most developed meta. Fucked up!

Others

Would be nice to hear from some Warcraft or C&C heads. Or some folks who played/watched the original Total Annihilation to see if the fixed camera and old-school map design meta affects information flow. Also especially interested to hear from some Wargame/SB/Warno players since the doctrine in those games seems overdetermined compared to something like Starcraft. Dawn of War 2 seems like more of a very focused micro contest, edging into fighting game territory. No idea what's up with Age of Empires.