I didn't know that Lego still had girl Legos. My girls hated them; they wanted the "real" Legos, the same ones that boys got. They also thought that the girl Happy Meal toys were lame. They always wanted the boy toys.
The truth may be out there but lies are in your head. Terry Pratchett
Most things I've bought for my kids are gender neutral.
Legos used to have Spiderman legos but no longer make them, according to Dylan. But Mega Blocks has them. http://www.megabrands.com/en/products/search.php?sys_h=1&fc=1&keywords=spiderman And Mega Blocks will interlock with Legos.
Angela built with Legos clear into her teens. She quit because she ran out of hours in the day. When she moved out, she gave them all to Dylan.
I agree in this particular area, but I'm not sure that all gender differences in children's play are forced on them. Both of my kids played with the Barbie house my daughter had, but they way they played was totally different. My daughter played the way you'd expect for a girl, using the barbies as people (or substitutiing other dolls that she wasn't afraid of--barbies freaked her out) and having them live in the house. But my son and his friends used the house like a garage that just happened to have a bathroom and bedroom. The elevator was to get the cars onto the roof of the house.