Disclaimer: ACKS is fun. I'm enjoying running it, and I think that my players probably don't hate it either (quoth Tim - "I want to try running an old-school 3.5 game in the fall. Wait no, ACKS is more fun.").
But sometimes, you just want to go all-out with the kind of shit we pulled in Starmada two springs ago. To find a crunchy, buildy wargame and go to town with it. Also because tanks and mechs and lasers and tech is just fun sometimes.
Basically, I've got two itches that I want to scratch:
1 - Gritty, nasty man-vs-aliens dungeoncrawling. Could be Space Hulk with expansions (namely: thunder hammers, autocannons, and the force bidding rules), could be a Star*ACKS one-shot with whole platoons of L1 marines-at-arms. Deathwatch is built for this, but it's too heavy for me. StarGrunt could work too, but it's lacking strongly in the aliens department, and our previous attempts at them... well, maybe could be tweaked into a workable shape. It also doesn't seem well-suited to indoor combat, though indoor games would be short and fast since close assault is where casualties really happen in SGII. SG also, of all of these candidates, has the least hidden information (though their artillery mechanic is a beautiful exception).
2 - Crunchy, heavy mechanized warfare. OGREs and other supertanks, mechs, guided missiles, attack helicopters (or antigrav equivalent), tactical nuclear weapons, ideally some form of campaign system, the whole shebang. BattleTech seems to be the most popular option for this in this part of the country, but what it possesses in wonderful construction rules it makes up for with a painful damage resolution system and a model of futuristic warfare inconsistent with modern facts (BT cannon ranges top out at under half a mile (~2400 feet), compared to modern cannons with effective ranges of upwards of two miles) and sometimes physics (melee mechs make me sad). BT's Operational Campaign system from Tactical Handbook is pretty sweet, though. Wardogs inherits a lot of BT's problems, and while generally lighter, is not well written and rather confusing. Dirtside would probably be great, since it has a construction system and seems relatively lightweight, but the randomization using chits is just... arg. There is also here the persistent problem of lack of models. Dirtside has more hidden information built in by default than most of the games in this category, though, between its beautiful objectives system and decent artillery rules. Epic suffers a similar miniatures problem, but does at the very least not use chits. You do have to deal with the default (crazy) assumptions of the 40k 'verse, though, and the rules are hard to find these days since the Specialist Games page was taken down. CAV could work too, but I'm pretty much unfamiliar with it except for a few reports from Sergeant Crunch. It does seem to be lacking in the construction system department, but the damage model is really simple and reminds me of Starmada Nova's to some extent. Guess I could hack together a S:NE ground project like I was looking at doing with Admiralty... Certainly the new Seekers rule would work nicely for guided missiles.
Anyway, I think part of this speculation and grumbling is that running ACKS twice a week means I'm prepping all the time. Switching one game a week to something more wargamey would mean that I could have a few days off to come up with ideas, rather than strictly reacting to my players. Variety being the spice of inspiration and all that. Or, if I can't convince people to switch to one RPG night and one wargame night a week, I might have to do something dangerous, like throwing Expedition to the Barrier Peaks into my ACKS world (though with the average Int score of this party, particularly Drew's henchman brigade, that would be absolutely hilarious. Hmmmm....).