Morning, @anarcat,
Here is a suggestion that would make it easier for you to decide.
Ask the print shop to send you a dummy in correct size, correct number of pages,
correct bindning (wire-o?). Or simply buy a copy of last year’s cal, to let you have the feel of the thing.
Do you have a (professional) paper shop nearby? Do they have a dummy shop?
Have fun!
Claes in Lund, Sweden