I love the detailed check in instructions, but for checkout it's just selecting a time. I put my checkout instructions on additional rules, but I think it would be nice if we could put detailed instructions through the site.
This is a business that I own and I run. Airbnb is simply a marketing platform. At the end of the day I don't want them developing or enforcing policy for me (such as overriding my cancellation policy which was done recently). Clear communication with guests is the key. Mine sign a booking contract with terms and conditions that clearly state that checking out later than 10:00 a.m. will incur a 1/2 day rental fee. They also get a "check-out list" that is customized to my home. I am in the process of setting up auto reminders with my email - when I get the booking confirmed, I will set it up so guests will receive an email with my list as a reminder the night before they are checking out so there are no excuses for forgetting.