Firstly, I think that 3d model works in regards to clarification of information, it gives the client, contractor, fitter a better understanding of the way the components are assembled. Being able to slice through a .DWF file online can be very helpful, in regards to a sectional view of a particular area of the construction / elements.
Secondly, having very complex arrangements display in three dimension, for example a multi faceted roof. Being able to display this in 3d really helps the manufactory of the roof understand the finished product/ building should look like, and the best pathway to achieve this.
Thirdly, being able to easily show changes to the model, for example if you wanted to change a hip roof to a gable roof this would take a matter of minutes, then updating the data drop to show the changes.
Fourthly, one of the biggest selling points of BIM is clash detection, this is simply combining the civil, architectural, structural, mechanical electrical model into one. Would be great to hear your thoughts on want works in your experience…