I put my two houses (same size and same neighborhood, walking distance to a university) up on Zillow and Craigslist 48 hours ago, with messages from about 30 people (half from Craigslist, half from Zillow) and 300 views each, according to Zillow. We'll do a showing this weekend and likely sign leases then.
I find navigating Zillow's rental page to be incredibly confusing and trying to reliably locate the # of property views was much too difficult. I got to it easily for one house, but then kept clicking back and forth on various pages to attempt to locate it for the other house. I wish they condensed everything to a single webpage that had all the information available, rather than various pages with tidbits and circuitous (and seemingly broken) routing.
I've never used Facebook to advertise a rental, but based on other random stuff (decluttering the garage) I've tried selling, Facebook people were much more flaky than Craigslist. One item had 8-9 replies, everyone swore they absolutely wanted it, please mark as sold, they are coming asap to pick up, and not a single person followed through. Based on that, and
@clarkfan1979 comment about discussion of the property online, I have no desire to attempt to go that route. Craigslist and Zillow work very well for me.