In reply to PJD:
The balcons are all great walks. Also great are walks from Montenvers station to Signal Forbes, from la Flegere or Index to Lac Blanc, walking up to see the Argentiere Glacier up close, likewise the Bossons glacier, the Aiguillette de Possettes which gives 360 deg views of both Mont Blanc range and Aiguilles Rouges. There are grade 1 scrambles that don't need a rope in the Aiguilles Rouges (which have stunning views back to the Mont Blanc range) - get a guidebook to locate the routes easily.
Via ferratas: they call the ladders down to the Mer de Glace a via ferrata but really it's just lots of ladders, but can be impressive enough to non-climbers. Nearest proper via ferrata is at Passy - info downloadable on-line.