Wales, you're right about the main theaters. However, some of the ships have additional conference rooms that are basically large blank auditoriums. I suppose it depends upon the ship. I've not been on the planning side of these, so don't know the particulars.
A nice, warm cruise sounds wonderful right now. Irene, if you can find out who shops Carnival, I'd be happy to split the room with you :-D.
(RCCL, Celebrity, Crystal, Cunard, Princess are shopped - not sure about the others.)
"Let me offer you my definition of social justice: I keep what I earn and you keep what you earn. Do you disagree? Well then tell me how much of what I earn belongs to you - and why?” ~Walter Williams