I have noticed that some kids are not allowed to have those kinds of sweets, some kids and adults are diabetic, etc. So, consider a fresh fruit tray and cheese cubes with crackers and nuts as their pre-snacks and during cake time snacks for those who need it.
So many times, I am rushing to get the present, get it wrapped, get gas, and find my way to the house so I miss eating lunch. Also, eating all that sugar on an empty stomach can give you a bad headache and/or make you very ancy, and then tired. So it is good to throw in a protein type snacks and healthier choices.
One other consideration, please don't get the cheapest cake you can. If it is dry and the frosting takes like a mouth full of sweetened lard, then your guests may resent spending their day to help you have a successful party and then be forced to eat that. If you notice a lot of uneaten cake on their plates, learn from ithat next time. That usually happens with white cake, and white or colored frosting combinations.