Here are some ideas for rebalancing, focused on what you're talking about.
Ragusa (Nikola Vitov Gucetic)
Start Bias: Coastal
UA:
Pearl Of The Adriatic
Cannot build Settlers or annex Cities. +1%
Naval Unit Production bonus every time you chop down a Forest, clear a Marsh, or connect a new Luxury Resource to your Trade Network. International Sea Trade Routes generate +100% yields, rising to +150% if you have a Declaration of Friendship and Open Borders or if it is sent to a Friendly or Allied City-State.
UU:
Trgovac (replaces Great Merchant/Settler)
Can be used for a Trade Mission. Additionally, may be used to Puppet a City-State or to create a unique Merchant House improvement. Within Ragusan territory, this has the same yields as a Customs House when built on normal terrain; however, if it is built on a Luxury Resource (not including Sea Resources), it connects the Resource, doubles the yields of the Tile and adds +2
Gold. When constructed in City-State territory, generates +10
Gold, +10
Science, and +5 Influence per turn as long as you are sending a Trade Route to that City-State. Max. one per City-State.
Gold yields of Merchant Houses are increased after researching Economics, and the primary Yield for the purposes of New Deal is considered to be
Gold.
UU:
Argosy (replaces Galleass)
+1
Movement. Gains a unique promotion, "Sword of the Rector", that grants a +5%
Ranged Combat Bonus for each Merchant House in City-State territory. Generates
Gold and
Trgovac points per kill. May be upgraded to a Trgovac in the territory of an Allied City-State for a large amount of
Gold.
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This build focuses on getting friendly with City-States as well as taking them over with the Trgovac. I'm fairly certain the new iteration of the UA is a bit more viable, though I'm not sure. The Argosy's been changed the most, but that's just to make it synergise a bit more with the emphasis on Trgovacs. The Merchant House has also been spiced up to make it that bit better when you haven't got too many nearby City-States - park one of these bad boys on a copy of Salt or Gems and watch yourself become a happy li'l clam. =]