Though I have been backpacking for several years now, this will be my sister's first trip. Only the Nice and Paris are hard dates. Any feedback would be appreciated. The 3 float days in the middle are assumed to be in the general region of Nimes, but we could also hop over to Carcasonne.
RJ
Day 1: Leave East Coast USA
Day 2: Arrive Nice, 10:30 AM
Day 3: Nice
Day 4: Marseille
Day 5:Marseille
Day 6: Float/Avignon/Nimes/TBD
Day 7: Float/Avignon/Nimes/TBD
Day 8: Float/Avignon/Nimes/TBD
Day 9: Paris
Day 10: Paris
Day 11: Paris
Day 12: Leave Paris (10:30 AM)

wildphatdisc
1
kira
#1's got it - Marseilles isn't that great a place to visit - a French friend on Tuesday was moaning about an enforced week with her in-laws there and said how awful it was!
If you want to see some countryside, I'd spend the two days you have planned in Marseilles in Carcassonne and then the night train back to Paris
Kira
Pro tip