You need to climb some passes, that's for sure. Best way is Petit St Bernard, that's right. But you have to ride Aravis and Saisies to get to there. If you don't like climbing you can avoid them, but you'll have some extra miles (visit my
homepage for profile information). After Petit St Bernard there's a long road to Aosta with a few tunnels, but you can avoid the tunnels: the old road is without tunnels, it's only for pedestrians and bikers. It's a little bit more time to get to Aosta. In the Po plane there are no further mountains. but sometimes there is a heavy wind and it feels like climbing. Good luck,
marmotte