You know how nuke has red/big rock jump? You should have like boat jump. Or maybe some kind of jump across a river canal, where if you make it, you get a major advantage in positioning; but if you miss, you fall into the water and are set back back having to take a detour.
Perhaps you could have two of these at the top of the map there. One on ground level. And maybe the other is from on top of that pink building (T side) diagonally across to the balcony of that nearest pink building. Here's the catch though: That other pink building has an upper level interior that is only accessible by a successful jump. Maybe then you can proceed to jump to the next building furthest on the left and get a back view of B.
It'll make for a lot of good tactics and stealth.
But you might have to shield the T's roof jump by a clothes line (or maybe a few clothes lines/other objects). That way CT's aren't just watching from CT spawn to see if T's are trying to execute the jump.
Oh and have you thought about adding a sewer system?
I just had one crazy idea that branches off from a sewer system. You could maybe have a section of the wall in one of the sewer passages that you can shoot and it crumbles that section wall to pieces, creating a hole. The wall could have a small crack (or a few), or if you wanna make it a small challenge for people, don't put any cracks. The this hole ends up being an old passage to the interior of a house. It could either lead to a cs_italy style wine cellar (would be just awesome if you completely copied italy's wine cellar) and there's stairs that lead to a floor board exit; or just have the passage directly lead to a floor board exit.
I'll leave it at that for now. I think if you have that exclusive T jump and a sewer system, T's will be a lot less hesitant to move in. You don't want this to end up a sniper arena map (Though it would make a pretty bad ass sniper arena map).
Oh and one more thing. It could either be good or bad, depending on one's personal opinions, but the map might turn out to be a short-lived he_grenade map. The solutions would be to make it impossible to nade over the roofs ( water sky =D ), or just stretch out the map.
I, however, like the idea that T's can risk wasting all their nades on A. And if they were to spam a few smokes or something during buy time, it would come at a cost penalty to their economy.
Anyways, looks like a really cool map. Looking forward to updates.
Oh and keep in at least one gondola! It aint venice without gondolas.