Love these stickers!
These are perfect for annotating things in the planner - I used the gift, cupcake, and balloon stickers to indicate birthdays, etc. on my monthlies. That way I can glance at a month and see the important days popping up. Of course, there are many, many ways to use them - and be creative! I think they are pretty essential, since they coordinate so well with the planner.
A side note: I am realizing that these simple shapes invite me to practice drawing in the planner also.