As others have mentioned, it varies. Too many factors (are we talking gutting the building and tearing out walls or just new furniture w/repaint), to the philosophy of owners.

I've stayed in properties under renovation numerous times. As a general rule, I try to avoid them. How management chooses to handle it will greatly affect your experience. Good management will do everything possible to isolate the renovations from the guests, to the point that you wouldn't even know there's any work being done. At worst... Well, you may find yourself in the middle of the work zone, with no working heat/running water/electricity and noise/dust everywhere.

The last one I endured was the former Radisson on 48th & Lex. It was being converted from a non-flag to a Marriott. Not a complete gut like the Intercontinental across the street, but more than just paint. Unfortunately, management hadn't yet been given the Marriott training and were clueless about the situation. I was put in a room directly next the elevators which were in dire need of new guide wheels/tracks, the temporary gym in the room directly above me, and the construction zone directly below me. Safe to say, it wasn't a pleasant stay. The front desk and manager-on-duty were very generous with the compensation, which I do appreciate, but it was something which didn't need to happen and could have easily been planned for.