I've rented apartments and houses from Booking.com and VRBO a few times each. To date, they've been good experiences but there's often some sort of slightly higher-maintenance aspect to it. Needing to go somewhere else to get the key, needing to somewhat clean the place before checking out, etc.

But depending on the location and size of traveling party, this can be a great way to travel. I've done it in both rural/lake destinations as well as cities. The one common theme is either (a) it's off the beaten path for my points/status chains or (b) it's a European city where I don't want to spend max-category points for a room that only sleeps 2 people comfortably.

I won't do the Airbnb thing.