In reply to simon manc:
I entirely agree with MG about the quality of the GP for walking; scenery and wildlife are fantastic. It pays dividends to make sure you’re fit before you go, or alternatively do some warm-up walking from a valley base to start with - Alta via 2 does involve some hefty grunts up and over the ridges between the main side valleys, your reward being a real sense of mountain travel. The end of July and August is the Italian high season; particularly at fine weekends the accommodation both in the valley and at the huts can be absolutely choc-a-bloc (well worth booking ahead if you can) and the usually high standards of welcome and catering can suffer as a result. The VE hut can be a real bearpit, and if you search the Forum you'll find that various folk have thought it preferable to climb the Gran Paradiso in a oner from the valley. Although there are good campsites in the valleys, wild camping officially isn’t permitted in the National Park so you need to use the huts unless you’re prepared to take your chance bivvying.