Residential units primarily. Chicago has received $1.2B in proposals to convert office space to residential apartments, for example. I imagine you might be able to convert to hotels as well, but admittedly I have not yet done that research.
I just read an article saying that the costs would be prohibative to upgrade office highrises into apartments.
Here is one that I just googled:
https://www.bizjournals.com/bizjournals/news/2022/04/13/offi...
I read another article about it being the same thing in Los Angeles - cost prohibative.