Put a "Yesterday" button on the booking chart
This was previously suggested a few years ago but was rejected by RMS to the dismay of many users, so after a few years it's time to suggest it again.
Out of all the systems I have used in the past 16-years the one feature that was the most valuable and helped with usability is the "Yesterday" button on the booking chart. It is in many other PMS systems such as Seekom for example.
It's a tiny little details but an extremely valuable detail.
In the morning you can see your in-out movement visually along with the status that helps prepare for your day before you actually do anything; you can get a snapshot of how to assign housekeeping staff; between opening and 11am when we're checking out guests it's 1 thoughtless click where coffee isn't required instead of 2 clicks that requires coffee to operate the calendar; when a super early arrival appears inbetween blinks of your eye, you can hit the 1 button to see if the room is vacant or if you have a late check-out still in the room.
It's a silly little button that improves the quality of life of this career manager and I'm frankly surprised that RMS doesn't have it as I'm pretty sure it's the only system in the past 5-years I have used that doesn't have it.