Now, my second time through, I'm /almost/ done with every achievement. I don't really care about recording my "best" times or anything - I just want the cheeeeeeeeeevs. MUST HAVE CHEEVS.
I've finished up all of the achievements except for keeping all the heroes un-incap during Belly of the Beast (I actually just saved half-way through so I /should/ be able to finish that up tonight) for the campaign storyline parts. I also need the Aces All-In (I think?) where you only use the artifact once on Hard?
I am probably going to have to do one more playthrough to get the armory upgrade achievements (I'm still missing vehicle and starship mastery) and I think I'll use that opportunity to also get Brutal Campaign Ace. After that, it will just be the Lost Viking Terratron and Speed-Run to go!
I'm actually kinda excited about all of this - although so many of the missions are just ridiculously easy to win with marine/medic/tanks.
If anyone has any cool tricks for the single-player campaign, leave them in the comments.