Himachal trip planned from 11th May to 20th May 2012 - Itinerary advice needed

Hi,
I am new to the site, amazed to see how people plan before moving out. All this while, I have being travelling on my car, and love road trips (not that I have traveled too much). But, this time decided to go budget and experience the train travel.

Himachal Tour, happens to be my tour after Amritsar Golden Temple and before moving to Agra from Kalka by train.

I have been suggested to take a toy train from Pathankot to enjoy the deep valleys along the route. I have not planned as to how do we go ahead and cover some scenic natural beauty of Himachal. Would also want to get to a place to where I can find some snow. I am travelling with my wife and two kids aged 13 and 08. I don't know if half day trek is also possible in my short trip. Also look forward for your suggestions to plan my itinerary starting from Pathankot on 11th May and exiting from Kalka on 20th May, 2012.

You may visit McLeodganj. It is less than 100kms from Pathankot. You can enjoy some treks there. But coming down to Kalka may be difficult from there. However, there are direct trains to Agra from Pathankot.

Note - there are two railway stations at Pathakot, one is the Pathankot Jn and another is Chakki Bank.