The Evolution of StarCraft
Ars Technica's Opposable Thumbs blog links to a piece chock full of gaming history. The StarCraft Legacy site offers up a historical record of the evolution of StarCraft . Written back in 2004, it is still relevant today. A game title that, lo these many years later, not only has an avid cult following but may be the most popular sport in South Korea is something you want to keep in mind. We may even hear word of a sequel this year. The piece runs down the numerous changes the game underwent, from the ugly alpha days through to the upheaval of Brood War (damned Lurkers). Tidbits like this make the article well worth checking out: "The game made a weak first impression at [E3], and it received much criticism. There were many remarks that the game looked too much like 'Orcs in space.' When Blizzard came back from E3 that year, they decided to scrap the idea. Their decision? 'Let's step it up a little more, let's revamp the engine, let's do more than what we're showing. We can't do Orcs in space.' Thus, StarCraft was reborn. The basics of the Warcraft II engine were still used, but more work was being put into the design and programming."
I haven't played Total Annihilation, though I've seen it mentioned on Slashdot before. I have something to pitch in here too, though, about another not-that-well-known RTS game, which I think is cool.
Dawn of War has no resource collection like you usually see in RTS games, instead, there are Strategic Points (plus some other similar things) on the map, and if your troops occupy them, you get more of the Requisition resource which you use to get more troops and buildings.
The Power resource is generated by power generators, which are buildings that you can build in your base (or on special places on the map).
Buildings are built by builder units, which build buildings and sometimes repair buildings and vehicles, but they don't gather any resources, so you usually only need a couple of them.
Also, instead of controlling individual units, most units are part of a squad, and you control the entire squad as if it is one unit. Characters (which don't level up like in Warcraft III, but can usually be upgraded) and vehicles are an exception, you control them individually, although most characters can be attached to a squad.
Squads can be individually upgraded, i.e. you can equip some of the members with special weapons, and you can even increase the number of squad members, so you don't need to produce individual units in your barracks and them move them to the front line, you can "build" the reinforcements right inside the combat.
All in all this makes the game much more action-oriented, with much less time wasted on resource collection and base building.
There's a demo, be sure to watch the intro movie, it's amazing. If you want to buy it, I recommend getting the Dawn of War Anthology set, which includes the two expansions. The second expansion is almost as expensive as the Anthology set, and includes a cool campaign, in which you can conquer the planet, and you decide which territories to conquer. The campaigns in the standard game and the first expansion aren't that cool.
I can't say much about the multiplayer quality, but there is at least one "cheese" map available, I'm sure you'll know it when you see it.
I suffer from attention surplus disorder.