WBD has to be well planned by the school if it is impact on children's reading, as does careful choice of a character, from a story a child loves or a new book to them, supported by parents.
Dressing as a footballer or princess (broad character, tv film linked) defeats the main objective - which is reading.
It is all very wasteful and full of consumerism, sadly.
In my own school, I knew children didn't have books and parents didn't have the knowledge or skill to support their child. I knew the WBD vouchers would be wasted. I knew children didn't really go into our local town and wouldn't visit the bookshop.
So that's what we did, a planned visit to the local bookshop, time to spend our vouchers followed by a visit to the library where we signed up for library tickets and listened to stories read by the librarian. Met the needs of the children and families perfectly.
A follow up session was planned a week later, where children did some work linked to their WBD book, talked with others, swapped them if they wanted to.
Best, easiest option out there, decorate a potato to make a book character. These were taken to school with the book; books read in groups, discussed and character shared.