Many RTS games have been influenced by other past games. Most of these will have been influenced by earlier C&C games, but more often by not, by the 800 pound gorilla: Starcraft. I say, ignore (well not ignore, but move away slightly) from starcraft, and take deeper looks at what many consider the finest RTSes (those of us with more refined tastes ) : Total Annihilation and Supreme Commander.
Many mechanics and game concepts were brilliant in there but never made it into other RTSes because "Starcraft didn't do it", which is a massive shame. In this case, the idea of note is the camera control. Most games, yes, even Starcraft 2, can let you zoom in for a closer look on your units. That is becoming an industry standard. But Supreme Commander innovated more with the extreme control of the zoom. The mouse wheel (or other button that you preferred to assign) let you zoom out... and out... and out some more, until you had a fullscreen version of what is essentially your minimap, but still with complete control of the battlefield.
More RTSes, and the next C&C, should have this tool.
More control of the camera/zoom, which is a sadly lacking function in many RTS today. It also allows for greater map control. Imagine this: you're focusing on your base, decide to go attack the front lines. Use the mouse wheel to scroll down, get transported to satellite view. Move your mouse slightly to the desired position, scroll up, bam, you're at the right place
I imagine this is a fairly resource consuming function to implement, having all those levels of zoom in a game. But it is worth it, as it is one of the best tools ever made in an RTS.
Video of the function in action. Although this guy could have zoomed out somewhat smoother