I ended up visiting over 25 colleges between both kids. They ranged from small LACs to large state universities. Coed dorms were by far the most common, but there were a couple of colleges with all women’s dorms or all women’s floors. I don’t recall any colleges with all male dorms or floors, though I’m sure they exist.
Bathrooms were mostly single sex, but I think it’s more and more common for there to be a mixed sex bathroom somewhere in the dorm. My D’s college let students vote on if they wanted mixed bathrooms or not.