We have both boy and girl toys due to DS and DD... and we let them play with whatever - they run around with dolls along with trains. I don't believe in banning pink/princesses or girly stuff (we have lots of non-princessy "girl" stuff like MLP, random dolls, tea sets included - although for MLP, both DS and DD have their own ponies) and both kids play with "opposite" gender toys all the time without a peep from us (unless there is a massive fight over something). If DS wants to run around with a baby stroller, we have no objection (unless he ripped it out of his sister's hands). If DD wants to lay out her own RR, we stay out of it - unless she ripped up DS's tracks to build hers while he was playing with it.
We had started out with mostly boy toys in the house, but DD made it very clear she liked dolls, pink and green, and as we let her choose her own stuff, I found myself acknowledging that she really does want some stereotypical "girly" stuff that I had no interest myself when I was younger - but then she runs around in an astronaut helmet with DS, playing space exploration too. And I also knew that DS would also play with his sister's toys.
