What is the etiquette on birthday parties? Read on please.?

I am throwing my 3 year old a Tinkerbelle birthday party but I want to invite a few boys. So far it is going to be real girly even with the princess bounce house (which they won't care) but my sister says that it's her party and all is ok for the bday girl to have her Tink stuff, but when doing favor boxes just to make the boys' filled with boy stuff and the girls' girl stuff. Is that the norm? Or should I be making separate boy "colored" favor boxes w/ the boy stuff? Is it ok to have the Tink favor boxes but with boy stuff? What is the etiquette for girly parties and boys?