My dream strategy game is something like a mix of Europa Universalis and Civilization and some of the grand strategy element of TW.
Maps: Maybe procedurally generated, I could settle for Earth, or smaller, Europe, etc. but there would be no grid, square or hex based. Instead, movement ranges are based on technology at the time, and other factors like equipment, weather, and infrastructure. Like civilization, you must build most everything (it could be a useful mechanic to be able to automate much of it, or save templates) including cities, roads, industry, etc. I don't know how micro it would get, but I would settle for just placing the city and determining how it grows via determining how it handles industry.
I don't know how I would want research handled!
Recruitment is more like EU, but based on local zones of city control, like Civ, but actual borders are determined through a unique treaty mechanic. In short, YOU GET TO DRAW THE LINES ON THE MAP. Which excites me. Terrain comes in to importance big time obviously. Anyways, recruits are formed up at cities before being grouped into regiments and armies. Armies have their own zone of engagement too, much like TW. There should be tools like HOI to be able to handles huge amounts of units without having to needlessly micromanage.
Anyways, the unique mechanic is treaties. Diplomacy is everything, internally AND externally. I imagine a game where you can negotiate anything. I have so much to say on this, I tried to make it once. Failed miserably.