The UA actually looks very, very good the more I study it. Due to the double trade routes, you could hypothetically have half your trade routes going to your capital, pumping it up, and half going out and making money. You don't have to worry as much about a bad start (unless it's a no city-states nearby start) because you can pump up production and food while using your other trade routes to make money. You can strategically choose which city-states to puppet for the most resource diversity. You'll most likely get your first puppeted city a few turns after Optics, which in a direct beeline would be...35 or so turns? That's a pretty fast city. And city-states are often located near Natural Wonders., and you won't have to conquer the city-state and take the diplomacy hit to get the wonders.
Tourism won't be a concern, even though you'll only have one city, because you can rush-buy cultural buildings in your puppets with and you can switch great works even in puppet cities. You can use the food you send in via trade routes to pump up your food, allowing you to run Merchant specialists (don't forget that puppet cities default to Gold focus, meaning they'll be running Merchant specialists too) and you can crank out the unique Great Merchants by the dozen, systematically puppeting all the city-states.
So, to sum it all up, Venice seems as if it would be awesome with that UA. Sure, it's a little weak in cities in the early game, but what it will do is establish a late-game trading empire and ride on a most serene sea of gold to a most serene Venetian Victory. Also, policy costs would be low due to one city. It seems to fill the culture/commerce spot a bit better than Morocco. Assuming, of course, that the UA as we know it is real.
