Would it put off a publisher if a picture book story showed both a parent and child being frightened of monsters? From one of your previous posts about layers of meaning, a child could read a whole lot of negative things into seeing a parent being scared.That is correct.
Most stories seem to avoid that by having the parent either absent, reassuring, or disinterested/disbelieving.Exactly.
Is this a tried and trusted formula, or is there some leeway - such as Michael Rosen's We're Going On A Bear Hunt?There is some leeway--there's some leeway in pretty much every "rule" out there. But this is something to be very careful with.
Let's think about We're Going On a Bear Hunt. Most children do not have a built-in fear of bears (the way many do of monsters); after all, many children's books are about cuddly bears. So bears as a plot element are not automatically the source of anxiety other "bad guys" are. The bear in this book offers a mild thrill --just slightly more than an excuse to play at running away-- rather than a source of real conflict. And there's a dose of humor in this book that takes much of the sting from the bear's tension.
The book also doesn't complicate the ending with psychological extras-- when the family is home, they're safe. Period. The book tells small children what they already know and want to believe-- that there are scary things out there, but home is absolute safety, like a law of the universe.
Older children, of course, can explore the idea that home is not so safe.
And very young children can also enjoy stories where the bad guy/source of fear is dealt with a bit differently (Go Away, Big Green Monster; the goblin story in Little Bear's Visit; There's a Monster At the End of This Book; Mrs McMurphy's Pumpkin), but it must be dealt with sensitively. If you can't manage to empathize with the fear that small children feel --to understand in your gut where it comes from and what allays it-- then don't write that kind of story for them.
Many writers seem to have an ideal age range--the one they themselves most strongly empathize with-- and it's an important thing to recognize yours.
Whenever you don't know your audience, you're writing for the wrong crowd.