GraniteStater wrote:* Engineers - speed up entenching and RR repair. -- I'm on the strategic offensive, per Patton to his men, I'm not interested in holding anything. RR repair - I'll send Beetle Bailey to fix the rails; a little tardiness doesn't seem to affect my overall war progress. For me, so far, not very useful.
Even if your corp or army only pause for a turn Engineers are working madly to improve your entrenchments. Also if you move into a new region with a minimal cost to enter it (in days), as soon as your stack stops moving it starts digging. Never a bad thing even if you are attacking. And just because your force is in offensive posture and the enemy in defensive doesn't mean that in the ensuing battle that your troops will not be attacked. Think of Chancellorsville and Bank's advance on Shreveport. Never deny yourself and advantage regardless of how small you may deem it.
GraniteStater wrote:* Naval Engineers - speed up shipyard work and repairs therein. Useful, but limited to a few "spots', plus I get 'em for free anyway, placed in the obvious places.
They also assist in cohesion recovery IIRC. Having them close to where the fighting and exertion is going on is a good thing. I always put one in Fort Pickens and then move it to New Orleans when I've taken that. I also put two in the twin forts at the mouth of the Mississippi to help keep the Gulf Blockade in shape in the most timely fashion. Especially important in the winter months.
GraniteStater wrote:* Medical - speed up recovery (i. e., it heals things faster). Only affects the stack it is in. Why bother? Yeah, I'll keep Grant in medical whisky (sorry, US, I know it's a canard). Would be a bit more useful if it healed all units in the Region.

Having your corp or army recover cohesion as quickly as possible is
important and can keep it on the move in good shape and save it from disaster. Even just marching over bad terrain or in poor weather can wear you troops down and leave you in a lurch right when you need them. What could be more important than that? other than supply?
GraniteStater wrote:* Balloons - improve intelligence for the stack/commander. Useful and relatively cheap. This is a good one.
Cavalry can do the same and reach out into the hinterland beyond the view of balloons to give you more information over a larger piece of territory. You just have a lot more to manage with them. Also the cavalry can tear-up the railroads behind the enemy thus denying him supply and the quick advance of support. Balloons can't do that.
GraniteStater wrote:* Signal Corps - helps with Command and Control (I think & suppose). Not a big bang for yer buck, methinks, as far as the actual improvement.
The extra command point(s - is it one or two?) can come in handy, but it's not generally something for which I plan. By mid-war I've usually got enough money and WS to be able to throw them out there along with the hospital and engineering brigades, but I don't really depend on them or plan them in. Nice to have, but meh. But every once in a while I find myself sticking one with a division that I need to post as a rear-gard because I don't have and extra general on hand. The difference between being at 100% command strength and losing 10% of a divisions power for lack of command points can be dangerous.
GraniteStater wrote:* Marines (Sailors) - USMC yes, but why build a Sailor instead of a Marine?
The Marines are tough - relatively high cohesion from the start - but relatively small and therefore not really stronger than any other first-line infantry regiments. But they also take a long time to build and you can't build them where you want. During one game I desperately needed (
wanted) a few Marines for their fording/bridging ability and built them in time for their deployment in an invasion force. Unfortunately some of them were built in St. Louis, MO and had to be transported all the way back to the east and missed the ship and the invasion
Sailor are not as tough as Marines and a little cheaper, but more importantly build quicker and almost always on the east coast. If you need fording capabilities quickly in the east, go for the Sailors.