mitsho
Deity
Public Fountains as a name would work, but it goes awfully close to the Garden, no? And I'd prefer to stay as close to the basic game as possible, especially with names, to keep the entrance bar for new players low.
I more and more like the Thermae as a Water Mill replacement. It does combine a production with a happiness building. But this then would be the first Building you'd buy in any city while still the chances are high that it doesn't exist in a conquered city (no rivers everywhere). Also, it works well with the UA that gives production (not
benefits) in all cities but Rome. Roman cities would be beasts in building up the economy. I'd see something like (after Thal's new system)
Thermae
replaces Watermill
and 
+ 3
+ 1
no river requirement
The only problem I see is that Rome imho should be the starting "conquest" civ just like Egypt is the civ for new players overall, and this UB could be played pretty wide...
As for the Dutch, I like any bonus that gives them yields on the luxuries themselves, as that entices them to build an empire "along the coast" and on different continents (and I hope we can introduce a better luxury spread all over the map-system).
The Merchant option is too strong since the Trade mission is balanced for one. That could give you much gold at once (instant = powerful, especially early on) and much over the game totally.
EDIT: Stalker0's idea works as well for me, since a) it's conquest oriented, b) markets/forum will be built early on by puppets so it's a building that doesn't require you to annex (which of course doesn't work with the proposed effect since that is not connected to puppet cities) and c) it fits with the idea of Romans as Social Innovators. Many of the civics can be applied to Roman Society and it did go from Tradition (Monarchy) to Liberty (Republic) to an Empire again, all the while being to a degree military oriented (Honor). So that fits. Maybe we can give it a double effect:
Forum
replaces Marketplace
, 
+ 20 %
+ 1
on luxuries
+ 1
if city is puppeted
City doesn't increadse Social Policy cost if not occupied or puppeted
I more and more like the Thermae as a Water Mill replacement. It does combine a production with a happiness building. But this then would be the first Building you'd buy in any city while still the chances are high that it doesn't exist in a conquered city (no rivers everywhere). Also, it works well with the UA that gives production (not

Thermae
replaces Watermill


+ 3

+ 1

no river requirement
The only problem I see is that Rome imho should be the starting "conquest" civ just like Egypt is the civ for new players overall, and this UB could be played pretty wide...
As for the Dutch, I like any bonus that gives them yields on the luxuries themselves, as that entices them to build an empire "along the coast" and on different continents (and I hope we can introduce a better luxury spread all over the map-system).
The Merchant option is too strong since the Trade mission is balanced for one. That could give you much gold at once (instant = powerful, especially early on) and much over the game totally.
EDIT: Stalker0's idea works as well for me, since a) it's conquest oriented, b) markets/forum will be built early on by puppets so it's a building that doesn't require you to annex (which of course doesn't work with the proposed effect since that is not connected to puppet cities) and c) it fits with the idea of Romans as Social Innovators. Many of the civics can be applied to Roman Society and it did go from Tradition (Monarchy) to Liberty (Republic) to an Empire again, all the while being to a degree military oriented (Honor). So that fits. Maybe we can give it a double effect:
Forum
replaces Marketplace


+ 20 %

+ 1

+ 1

City doesn't increadse Social Policy cost if not occupied or puppeted