Take the Disney movie Cars 2. There is a lego set which has a quite big model of big ben and the car characters from the movie. DS was given this, it is really lovely and he plays with it for a long time.
It would be appropriate to make a lego set of Rapunzel - ie build the big tower, have a rapunzel minifigure, a witch minifigure etc.
I have a DS and a DD and the facts are whilst DD enjoys playing with lego, DS gets far more fun and spends far more time doing so because lots of lego is stuff that appeals to him - Cars 2 movie, helicopters, other vehicles etc. We also have basic bricks, but actually both my DCs prefer the sets that have instructions. DD will play with the Cars 2 lego, happily but she would be far happier building the rapunzel tower.
This is just how they are, I haven't done anything to influence their liking for girls/boys toys - obviously there is a mixture and they will usually go for their own stuff, with the exception of truly gender neutral stuff like octonauts toys.