There are some areas which will hold fresh snow longer than others and, like all ski areas, you’re more likely to get powder higher up.
The Grand Col is an off-piste playground. The lift is small and slow, which can be off-putting, but there are typically less people on the two (one red, one black) pistes than in the off-piste areas surrounding them. Because the whole area is above 2500 metres it receives, and keeps, more fresh snow than most other areas in the resort. Be prepared for the very flat (if not slightly-uphill section) towards the bottom of the red run, you’ll need some serious speed to traverse it without undue effort.
Similarly, but a bit lower down, there is plenty of off-piste accessible from the top of Arc 1800’s Vagere lift around the Golf and Vagere red runs. There are some hidden streams towards the end of the Golf run however so, as with all off-piste skiing, exercise caution in areas you do not know well.
For beginners who want to try some off-piste, they should try the wide-open area above Peisey-Vallandry, around the 2300 lift. Although largely groomed, there are some patches which are left unpisted, and can be great fun immediately after a snowfall. You’ve got to get up there quickly though!
If you like dodging the trees, there’s plenty of forest near the Derby lift which can be successfully negotiated by those with the requisite skills. There’s also lots of other woodland leading down to, and beyond, Arc 1600.