UI:
*numeric overlays over skill and research bars (so we don't need to hover for info) also make it an option
*construction completion bar for each city in cities tab (bottom ui element), also open that city with double-click of the icon
*sovereign spell hotkeys both for strategic and tactical
*hotkeys for top ui buttons (options/report/cities/spells/crafting/rivals) ; f1 - f6 perhaps
*an option to display FPET(food/production/essence/thralls) information on strategic map near city flag
units:
*remove swarm ability for bow wielding units; feels awkward
quests:
*quests from Rivals should pop up closer to player territory, especially kill quests. Sometimes these are difficult to deal with on medium and larger maps. Delivery quests are easy enough to complete with scouts.
*Faction and/or sovereign specific quests which are a bit more epic in nature (many multiple steps)