I would think you would use multiple UUs for leaders in different eras: like George Washington having a Minuteman UU and Roosevelt having a USMC UU. Or Elizabeth could have some kind of upgraded frigate and the Redcoats could be given to Victoria.
I'd throw in a Monitor UU for Lincoln. As the UU for the American civ available to all leaders, I would favor a super-carrier which carried an extra airplane, but I could see a case for a B-52 or F-15 instead.
For England I'd give Elizabeth a Sea Dog- a caravel that has some sort of attack bonus, or the privateer abillity to convert enemy trade routes to cash. Victoria would get a redcoat rifleman with a white pith helmet, and Churchill would have a Spitfire.
I could see England having a number of possibilities for it's standard UU
- Musketman Redcoat, Longbowman, frigate, Ship of the Line, Dreadnaught, Special Air Service commando ... even a spy with a counter-espionage bonus.
Some civilizations still might have only one UU. Julius Caesar and Augustus both were from the same era of Roman history (End of the Republic), and used the same kinds of troops.
Quite true. I think I'd add an onager UU for the Roman Empire.
I'm still not sold on the unique abilities on top of UUs, UBs, and leader traits--it might be too much. I definitley would not use them as a replacement for any of the above; Rhye added them as a substitution to the leader traits, and I'm just not sold on it. Feels like I'm missing something when I play.
I think Civ will keep all religions equal, and let the rest to the modders. Agreed, Unique Abillities are questionable.
Balance might be maintained with one additional layer. I toy with the idea of classifying the civs or leaders as Herding/Horticultural/ or Seafaring, and granting them an extra hammer? for each animal tile pastured , seafood netted, or cereal grain farmed.