Over the past couple of weeks I have had quite a few emails land in my inbox about using AIM as a way to visualize 3D models and content coming from Civil 3D. Fistly, I have to say we love seeing these emails as they help to validate how powerful a tool like AIM can be when matched up with an incredible design tool, like Civil 3D. I would say that the effectiveness of the two is greater than the sum of their parts.
Having said that if you have "played" with the 2013 releases of AIM and/or Civil 3D, maybe you have noticed the new "Export IMX" button in Civil 3D and AIM as well as the import IMX capabilities in both. IMX is the new exchange format that allows you to exchange ALL relevant 3D content and metadata used by both apps. So, while the 3D model import/export capabilities work well for both AIM and Civil 3D, because IMX was built from the ground up to deal with the complexities of exchanging infrastructure model data, it does a better job in most cases and is more flexible than other 3D model types.
There is a great video tutorial for exchanging data using IMX found here:
I hope you find this as useful as I do. Cheers!