We use a heavy and a light task mgmt system to track everything that comes in from a reservation; from payment dates, to accounting entries, verification of cleaning appointment, review timelines, etc. It works for us and I am not suggesting replacing it inside OR. Although that would be an intriguing idea in the product roadmap.
In the shorter term, it WOULD be nice if we could perhaps have a place to enter special requests and, ideally, set a reminder for it. For example, special birthday, wedding (we have had 3 in our cabins this Summer alone), anniversaries, early check-in request (based on availability), perhaps they are having groceries delivered or renting an assistive device or medical equipment, etc. Things that need our attention prior to the guest arrival. These items could even be part of the DAILY CHECKLIST report.
We store this info in Notes, and if we have an associated OmniFocus task or Apple Reminder, then we add the link to that item. But then have to remember to look at the notes. That is where we sometimes fail, because a reminder is not set in the other task system or personal calendar. The other issue with notes is we record a other info in it, such as text messages not captured, descriptions of interactions, and such. For some, it can be too much to just include the NOTES in the Daily Checklist report.
Given the plethora of great web services for reminders and task mgmt, perhaps you could just integrate with an online task manager. Not sure if writing an integration and using it would be easier in the long run that building it in. That's a decision for the team there.
What about using a custom field? Use it as a basic text entry and include the notes you'd normally want reminders for. Then set up a trigger to email YOU a week/day before the stay and include that custom field in the message thereby reminding you to take an action (order linens, order birthday cake, drop off wine, etc). Custom fields can already be included in daily checklists too.
I agree with some sort of reminder triggered for a custom field. I setup a custom field for Special Requests and then created an email with a trigger. BUT, if there is not a special request, then it's just one more email to ignore. Personally, I'd like the option to include the custom field in the Booking Fields of the Triggers where Custom Fields are listed, can be selected and then some sort of IF statement logic. It could be as simple as IF custom field is not Null then send trigger or something like that. I'm thinking of something like custom formatting functionality found in Excel or Numbers.