We all know that boys, by and large, love our toys, but let's not assume the girls won't be interested.
Daughters and granddaughters can go for model railroading in large numbers, and so can the occasional wife and sister.
The girls may naturally focus more on the little people (like playing with dolls) and the arts and crafts involved in model railroading. That is true of my 7 year old granddaughter, and was true of my 32 year old daughter when she was a little girl.
They also enjoy Polar Express excursions on tourist trains, which we are considering doing as a family, and steam engine rides.
The girls may be an untapped market in the world of model railroading.
Pastel colored toy trains for girls, however, is not the answer. LOL, Arnold