In reply to andyd1970:
I used Alpi Canavesane 08 MU Edizione 'Carta della Valle d'Orco' on a recent trip to the south side of the national park. Just walking, not climbing Gran Paradiso.
At 1:20,000 it's pretty detailed, and said by locals to be the best map of the area.
The particular sheet I had does cover GP, but only just. To the north, the sheet ends at the peaks of Petit Paradis which isn't much more than 1km north of the main peak. You get a lot more coverage of the southern approaches but there's enough of Valsaveranche to be useful - if that's where you're going in from. You get Refugi Vittorio Emanuelle, and the whole of the voie normale, which is marked as a path on the map (probably fair in summer - you can see the footprint trail on the glacier from miles away!)
