If I was a bbs warrior i would.
1. Increase down times of cities and factories.
2. Add a cement factory that increases down time of towns.
3. Add a % needed variable to control the number of town buildings down needed for capture.
4. Add a flag that went down, or changed color when the town was surrendering/ready for capture.
But I don't know why I post these ideas, HTC never will do anything about it.
HiTech
What about this? Cement Factories would affect towns, rail yards would affect the down times (on top of the increase to their "natural" down times) of the Cities (assuming you revamp the old city strats and re-add them), Industrial Center (IC) at the Capital and supply lines, and Power Stations that would affect HQ down time.
An example, You knock out the rail yard for a zone (which would stay down the same amount of time as the other strats but is affected by damage to it's zone City/Capital's IC). Instead of a convoy of trucks (to bases) and trains (to Cities, factories and the Capital) leaving every, say 30 mins, they will leave to supply every 1 hr. Fuel Factory is at 5%, rail yard is at 8%; You would have trucks carrying fuel, but they would only make their supply run every 1 hour. Meaning, the down times of the fuel at a field would be, say the standard is 1hr dt, tack on 30 mins for each, a total of 2 hrs. So if just the rail or fuel were hit, the down time of the fuel at a base would only be 1 1/2 hrs. This is a very crude idea, but I drool at the thought of hitting AH rail yards. *drools*
Now for the Power Stations and the HQ: There are maybe 3 power stations that "supply" the HQ (with a down time the same as the other strats but can't have their dt's affected by damage of rail yards or the Capital's IC). The HQ is no longer resupplyable, but just knocking it down without hitting the power stations, it would only stay down for 15 minutes. Hitting each power station would increase it's down time by an 15 minutes. Hitting all 3 and dropping the HQ would keep the HQ down for 1 hr. To offset, the power stations would be tough targets (requiring 1-2k to drop the main buildings and the flak would be moderate-heavy), spread out through out the rear zone (while still close to the uncapable bases and HQ) and fairly decent in size (maybe a half to 2/3rds of what the Capital's IC is. Wonder how we could factor a hydro dam into this...

).
Great, now I want to load up the DOS version of B-17 and go hit some Power Stations...*drools*