Now I would like my 2D cuts. By this, I mean I would like to look at a 2D cross-sectional drawing of my design. This may be at the XY plane, YZ plane, or some other arbitrary plane.
Most 3D modelers can do this, but when you make the 2D cut, you're often exporting the cut to a new file. If you change anything in the design, the cut does not update, and you must "re-cut". This is what I mean by real-time.
Good 3D modelers don't do this well, and poor 3D modelers can do this exceptionally (I'm looking at you Revit). Some can do both, but they're incredibly complicated and cost tens of thousands (Digital Project)
Have you tried Chief Architect? It works rather well in this respect, it's really made for ease of use. I don't know how well it would scale for large projects though, I've only toyed with it for small residential design. Plus the estimating and electrical/HVAC tools are poor to non-existent.