Another change I would like to see, especially within MP play is that when I initate the Diplomatic screen, I do not reveal all the Tech's I have just because...
Against the AI, one assume it knows ALL things but is constrained bu other things to not abuse this type of thing. When I open a Diplo screen vs the AI, I get to see "where his/her Tech" level is. Instant information that I probably should not be privy to.
When playing another human player, I do not wish them to use the Diplo screen as a window into my Realm, without my consent.
Not sure how to deal with it but I guess we could use a check box system, that any item I check the box on, gets revealed as available to trade, or be negotiated for. If not checked, it is hidden from the other opponent, thus keeping my Techs, # of Cities, and even Troops count secret, UNLESS, I decide to reveal that info.
The use of Diplomacy could even be applied in this area to have certain Techs, low-Mid level say, be always check boxed, based on the Level of Diplomacy you and another faction currently enjoy.
Good relations would reveal all low level techs by default. Mid level relations, the next tier is revealed, then when you marry in, all is revealed.
Just something else to consider.