That’s looking pretty good for starters.
I think you may find it helpful in future either to name your numerous numbered Groups (so you know in Outliner what is what) and/or make them Components. As far as I can tell, there is only one small downside to having components instead of groups, even if there is only one instance in the model, and several upsides. The only potential downside is that you may not want all the permanent fixtures to list in the Component Browser, once your main focus becomes on the set design, not the permanent features of the building.
And I note one small drawing error - the pillars in the wings are drawn with the back faces outside (showing blue). Not a major issue, but if you get round to texturing or materials for the building, and then rendering, it can cause problems.
Again, once you’ve more or less finished modelling the building, you might want to revisit the outline structure, and probably Lock all of the fixed elements. That way, you won’t accidentally move anything when drawing sets, and/or positioning cameras and lights.
You are fortunate in having a relatively high proscenium arch at 20’6. Ours is only a little above 12’, and is a real difficulty when trying to fit even a two storey set, let alone (as we have to next year) a three storey one. Views from our back row severely limit what can be seen of the actors heads when they are on the upper level upstage, if the upper level is to be high enough to let one walk underneath!
FYI I’m uploading here our main stage and auditorium model. You’ll see several different viewpoints in scenes, and the layer structure.
When imported into a drawing for a new play, I have all the building structure locked, but this version is the one I keep aside and update separately.
You may also note as you orbit around, that I have made some of the outer walls transparent when viewed from the outside, but opaque from the inside. I find that useful, and achieved it by applying different materials (one transparent, one opaque) to front and back faces. You can do the same even on a two-faced wall with thickness, if you treat each face the same way.
Stage Plan and auditorium.skp (2.2 MB)