You guys know you can force AA in the Nvidia control panel in specific applications, right? I have no idea why they disabled AA in DX9, but you can definitely force it and it looks just as good (to me anyway) as in the DX11 in game AA options. Granted you don't get all the benefits of DX11, but at least all the edges are smoothed out.
Now this is obviously going to put a strain on your graphics card so if you're running Civ 5 on a graphics card that is between minimum and recommended, you might get some lag. For the Nvidia side, this will probably work best on a 200 series card. Not sure if you can force AA with ATI drivers.
You noted that the shadows were great in DX11, but you it doesn't appear you even have them turned on in DX9 from looking at the screen shots. The only difference I can tell between Civ 5 with forced AA in DX9 and Civ 5 with the AA in DX11, is that there are no reflections in DX9.
The shadows are very light, but present, in DX9 mode. At first glance I thought they were missing too. I completely agree with this post by the way, DX11 will give you that extra bit of eye candy but if it runs slow for you definitely use DX9 and force NOT ONLY anti-aliasing but 16x anisotropic filtering as well for super crisp textures (just look at those farms
