Teresa,
Which France tour are you taking? Here's a few thoughts on the methods I use.
"Packing Light" is most definitely Step 1. You'll be carrying your own bags from the Bus to the Hotels, and in some cases this will involve a lot of stairs.
Pack so that you can keep "essentials" including clothing, toiletries, etc. close to the top, so that you don't have to pack and unpack your entire bag every time you stop at a different Hotel.
Before going to bed on the evening prior to departure to a new location, get your bag(s) sorted and just leave essential items accessible. After breakfast you'll be able to pack it quickly and get down to the Bus.
I always take a Daypack (as well as my Camera gear) on the Bus, while the main pack goes in the cargo hold underneath. I always keep at least a water bottle (which I refill for the day at each Hotel), some gum or mints, Handi-Wipes and a few other incidentals in the Day pack.
It's a good idea to keep a coat with you also, as you'll be stopping for day tours along the way (usually for a few hours at a time). If it looks like rain, take your coat "just in case". If it's underneath in the cargo hold, it won't be as easily accessible.
If I think of anything else, I'll post another note.
Happy travels!