Nov 26, 2013 - 1:30 AM
A Swiss Half Fare Card would be fine for your trip, provided that you will only make short trips from Grindelwald. I don't know what the Garcia Express is. Did you mean Glacier Express? If so, it would be a really long trip from Grindelwald to do even part of it. Also, with such a long trip a Swiss Half Fare Card would most probably not be the best choice. If you want to do this I would advice to first create your itinerary and then select a rail pass.
Train tickets that require seat reservations are indeed only available from 2-3 months prior to the travel date, depending on the exact train.