The Grand Balcon Sud is a path which runs high along the side of the Chamonix valley from Brevent to Lac Blanc. There is another very good path on the north side of the valley, but the southern path has marvellous views of Mont Blanc and the Augille du Midi.
The best way to walk the path is to take the cable car from Chamonix to the station at Brevent and then walk north along to La Flegere. This will take a few hours. From there you can take the cable car down to the valley floor and catch a bus back to Chamonix. A better idea is to walk further along the side of the valley and another 500 feet higher to Lac Blanc. There will usually be plenty of snow around even in July. When I was last there the lake was frozen solid. From the lake you can turn south and walk to the station at L’Index, then catch the cable car down via La Flegere. The path is easy enough. There is one short iron ladder to climb and poles are advisable for the sections that are still under snow. The reward is superb views across the valley. If you do the walk later in the day you will probably be able to see the paragliders launching from Brevent.
There is plenty to do in Chamonix and you can easily spend several days there. There are lots of hotels and booking is not usually necessary except in August when the French take their holidays. I usually stay at the Sapiniere. The people are friendly and it’s in a good location.
For people from the UK Chamonix makes a good stop on the way to the Dolomites. It’s about two days drive to Chamonix from Calais with lots of good places to stay along the way. When you leave Chamonix the entrance to the Mont Blanc Tunnel is only a few miles from town. Once through the tunnel you can soon be on the Italian motorway network and in the Dolomites in the same day.