You're right, as I recall RayDream didn't have rooms, per se, but there were individual modelers.  RayDream 3D, which is what I started with only had the splne modeler, but it was called something else -- freeform, maybe?  The Vertex modeler was a different sub-program, one that had its own set of tools and workspace.  They just didn't call it a room.

Hadn't thought of the price comparison to XSI.  Of course, I haven't paid full price for years; just upgrade prices, and DAZ practically gave me C6P, and I'm not complaining.

Yes, I'd also agree that Carrara is more geared toward inexperienced 3D folks; as I recall, the mission of RayDream was to bring 3D art capabilities to everyone.  And Carrara stays accessible for casual users.

Interesting idea about different levels.

 - Dex