We booked this tour through our Hotel but there are numerous coach companies offering the same thing at around the same price. We paid 33.50 euros each - child prices are 19.25 euros which includes your entrance to the Hohe Tauern National Park. Our guide for the journey only, was German but had lived and worked in Austria for a number of years thus his knowledge was both interesting and informative - with some humour thrown in as he told his stories both factual and fictional in German and English. The coaches are comfortable and have welcome air conditioning. If you want to travel a little further on the road you can take the free shuttle bus from the lower visitor centre - its not really free - you will have already paid your park entrance fee in the cost of your ticket.
When you are at the Franz Josefs Hohe viewpoint, there is actually a path leading down to the glacier below where you can get really close up with one of the natural wonders of Austria. When you are walking down, be careful with the path and it will also pass through some underground areas. Only go down to the glacier if you have enough time to catch the bus back to the towns e.g. Zell Am See (see my transport tip).
If you are driving a car or motorcycle, then it is possible for you to drive the Grossglockner Road. The roads are very well paved with clear directions, the only dangers are negotiating the bending roads, up-hill slopes and icy conditions when snow is still around. Also, the park charges 28 euros per car and 18 euros per motorcycle to use the road. As to the period of closure of the road, you can check the website below. When I was there, I noticed a lot of motorcycles and cars were on the road. In addition to the dangers above, do wear warm clothings if you are riding a motorcycle because the wind can be strong and cold up there. Oh yeah, another way is by cycling but it will be tough (I have seen some cyclists going up there).
If you do not intend to drive, then the only way to experience the Grossglockner Road is by comfortable air-conditioned bus of the Austrian OBB Postbus service. There is a regular once-a-day OBB Postbus (Number 651) which runs from the town of Zell Am See (the bus stop is just across the road to the Zell Am See train station) to the Grossglocker Road ending at the Frank Joseph Hohe viewpoint where you can see the beautiful Grossglockner Glacier as well as visit an exhibition building on the Hohe Tauren National Park.
More information about the bus schedule is at the Postbus website below. It is very important to note that there is only one bus per day which starts at Zell Am See around 9.20am and reach the Franz Josefs Hohe viewpoint around 11.40pm. The return bus starts at the Franz Josefs Hohe viewpoint around 3pm and reach Zell Am See around 4.40pm.
This bus only operates from the first week of June to end of September (and the start and end dates vary every year, so it is important to check the Postbus website below. For example in 2007, the start date was 7 June 2007 and end date was 30 Sep 2007). Cost per person is about 16 euros return
The bus number 651 schedule can be obtained from your accomodation if you are staying at Zell Am See.
If you really do not have any other way to get to Grossglockner and you have a full day to spare, you could always take the Austrian postal bus from Zell-am-See. It visits about a dozen small villages along the way. The bus starts out from Zell-am-See train station twice daily at 8.50 and 9.50am. You get about 2.5 hours at the mountain before having to catch the return bus at 2.45 or 3.45pm. Round trip cost is 16.70 euro.