1. Using curtain wall is fine, too. It's easier to create the support grid using mullions. Create a curtain panel family, offset the panel plane, and extend the edges to overlap the mullions for butt joint or lap joint conditions. Downside is that you have to manually coordinate the fenestration.
2. Using wall assembly layers simplifies coordinating location and fenestration. You create an Air layer as the placeholder for the support grid. You can either use details to convey the support information, or model it by non embedded curtain mullion, or structural framing using custom members.
