Well hell .... just design a generic terrain for each setting and be done with it.
Pacific
Western Euro
Eastern Euro
Med
Africa
Design them to be "perfectly even." (Both sides get exactly the same number of fleets, bases,ports, spawnpoints, strat, ack, aaa.)
Give the bombers enough room to up from rear fields to bomb strat and base their planes there. Give the fighters enough bases forward to always have a fight handy. Give the spawn points enough room from each other so they don't basically "spawn and camp" or "spawn and capture." Have the fleets spawn in "neutral locations" (NOT right next to a base or port anywhere).
All settings left "CT standard."
Then let the planeset define the time period.
But I'll tell ya something. It's nice to have an historically accurate map to immerse in.
Lastly but not leastly .... BEER.