I'm not sure if this was ever mentioned here but I really like the way Three's Company did their set design. Some episodes that come to mind is the airplane episode where Jack takes a tranqualizer. Some others would be the "Downhill Chaser" and the Camping episode. I think they did a great job with the design while maintaining the theatre performance look.

Yes, you're absolutely right!

And in general, the theatric nature of TC is very underappreciated. Though everything -- the plots, the delivery, the facial expressions, the mode of filming, the backgrounds of several of the lead actors -- belongs more properly on stage.