Hotel Owners- What do you wish you knew before you opened?

I am developing a property on the Oregon Coast, (U.S.A.) and am currently writing my business plan. I have traveled all over the world, worked in several American hostels (IYH affliates) and a few international ones (Tel Aviv and London) that were private.

The biggest difference between my past travels and current travel options that I am hyper aware of is social media (I was lugging around a dog-eared Lonely Planet!) but I've since been an AirBnB host, so I think I'm not too far from the internet realities of a happy/unhappy customer.

I feel like I have a solid idea of what is needed, and own a commericial building that will need some tweaking to get it ready. I am incorporating a wine and beer bar/lounge that will be open to the public at least part of the time, but otherwise, the standard stuff found in most hostels (maybe some kayak rentals).

I'm quite sure I need a wake up call...

Soooo, what suprised you the most?