Here is some suggestions for a more flexible and usable monthly booking calendar.

1. Making it better looking for enduser

I would like to be able to see support for the following:

a)
Instead of having small colored square, clickable, for available days, I would rather see the whole day filled with one color. Then the whole day should be clickable if available. And this color should be easily configurable from the stylesheet.
The benefit of this would be better looking, and it would be very easy to make the calendar smaller... since there is less elements within it.

b)
If #a could be implemented, then it should be possible to optionally only show the date within each day. This would make it even more better looking, and would again make it simpler to make calendar even smaller, if wanted.
If we follow the example from #a, with one color for available dates (e.g. default nice green), and optionally set future and current occupied days with a red color....
AND now use one TEXT (date) color for the dates belonging to the month, and another TEXT (date) color for the other dates (either belonging to month before or after)....

c)
I would also like to see changes in the way the calendar displays if you have clicked the FROM booking date, .. and now click NEXT month below the calendar, or selecting from the drop-down list above the calendar...
I do not want dates from next month to be added to the dates from the month I last saw.
When I click next month... I will see next month.. period.
Now the calender only grows... so a month is not a month... confusing for the end-user (unless you know how it works)....
And technically... it should be doable.... the Booking application knows which FROM date you have allready picked... and the user KNOW which date he first clicked on (if he forget it... he can just take a look at the FROM TO fields above the calendar...

Anyway.... it should be easy to customize the colors mentioned above.
It should also be possible to optionally choose to only see dates within each day. That is, only a digit, and no month letters.

If the above is implemented... then it should also be possible to via CSS to easily configure the size of the calendar. I like it when end-users do not have to scroll up and down to be able to continue using the calendar after e.g. selecting a new month.

Since the Monthly calendar (according to the above solution) only shows one month at the time (with other colors for month days before and after current month (only for the weeks belonging to selected month)... then it should be super-easy to make it so the Month is updated using AJAX... so if you look at a month, then click next month... then the page should not load... only the calendar should change.

With the possibility to get a smaller and better looking calendar... then the calendar should be possible to position other places in the booking page.. (object page).... My customer would like to see a small calendar next to the main image of the object. Where the Properties and Files are placed today.

And please fix the issue that it is not possible to book the current day. It is very strange that this is not implemented. It could be optional though.

Hopefully this can be implemented in the next couple weeks or so? :)