We are in Salzburg for one full day and were considering going to the Hallein Saltmine and the hellbrun castle. We have grandparents (very energetic) and a 12 year old and 15 year old boys. We are staying near the train station for 2 nights but only have one full day. Is this too much for one day? Is there anything else we should do? Is the Salzburg card any use for transport to the saltmine?