Roaring Camp Railroad in Felton, CA is a hidden gem in the Santa Cruz/Los Gatos mountains. They have a reception venue called Bret Harte Hall that can seat 250 people for dinner and it is quite charming. You can also get a Steam Train wedding package that includes a ceremony at the top of a hill. The bridal party and guests ride the train up to the ceremony site and come back down after the wedding for reception at the hall. How fun!
Venue website - http://www.roaringcamp.com