There are several good options for producing a strong economy.
- Ahmad al-Mansur, Morocco
- Extra gold per trade route with other civilizations
- Unique tile improvement (Kabash) adds gold to desert tiles
- Darius I, Persia
- Golden ages last 50% longer (during golden ages, you generate more gold. Also, when playing tall, you are more likely to hit more golden ages.)
- Unique building (Satrap's Court) gives more gold. Also allows you to hit golden ages more often by giving happiness.
- Enrico Dandolo, Venice
- Double as many trade routes available
- Unique unit (Merchant of Venice) replaces Great Merchant and gives you double gold for trade missions with City States.
- Venice is extremely strong for producing gold, with the notable downside that you cannot build Settlers to claim additional land.
- Maria I, Portugal
- Gets additional gold per trade route (based on how many different luxury resources you have)
- Unique unit (Nau) can produce gold, once per unit.
- Pachacuti, Inca
- Roads/Railroads on hills are free and half cost elsewhere. This means more gold per city connection.
- Unique Improvement (Terrace Farm) can help you play tall even though you have a lot of hills and mountains in your territory.
- Pedro II, Brazil
- Unique improvement (Brazilwood Camp) generates gold in jungle
- Wu Zeitan, China
- Unique building (Paper Maker) replaces the library and generates gold instead of costing gold maintenance.
I have not played all of these myself, but in my experience Darius I from Persia is an excellent civilization for playing tall and generating gold. The golden age benefits can be quite significant for your gold output. Venice is a very strong gold-focused civilization, but it is quite a different experience than others since your only way to get more cities is through war or purchasing city states (with the Merchant of Venice) and even when you get more cities, they will always be puppets.
I also suggest founding a religion and choosing the Tithe Founder Belief. Especially when playing tall, you can get a lot of gold from followers in your cities and you don't need to actively spread your religion beyond your lands.
Barbarians are always a bother in every Civilization 5 game I play. Even when playing tall and not focusing on military might, you need to build a few military units and place them around the land near your cities. Barbarian encampments only appear in places that you cannot see, so spreading out some units so that you can see as many tiles as possible vastly decreases how many barbarians will come your way.