Train travel and car rentals - Alsace and Luberon

we would fly in from Paris and take the train to Colmar.

Do you really mean that? Flying from Paris, if so to where?
If you are getting a flight to Paris, or are already there, better to take a train to Colmar from Chrles de Gaulle airport, or central Paris depending on wherever you are.

Otherwise plan looks good.

I edited that....thanks! Flying in to Paris from Canada.

Per Google Maps, drive time from Eguisheim to Bonnieux is 6.5 hours, plus time for stops or possible delays. Yes, there are tolls. But I'd prefer this to the process of driving to and checking in and out of the car rental offices on both ends, transferring luggage, and paying for train tickets, all on one day.

Did you price out a single car for the whole trip? I would not expect any higher drop fee and car rentals often have weekly discounts, e.g. 5, 6, or 7 nights all the same price. Avis is the closest to Colmar train station and also present at Marseille airport. You could get attached to your "home on wheels," and stock it with a few supplies (wine purchases, diet Coke, muddy shoes, maps in a handy spot), that add to the inconvenience of changing mid-way.

Last time I checked, maybe a year ago, there was only one car rental agency in Colmar. Consider taking the train to Strasbourg instead. There are more companies and you are more likely to get the car you want at a branch that has more cars on hand. It's an hour's drive on the autoroute (no tolls on that section).

I use autoeurope.com (a consolidator) to start, then compare with each company's website. Autoeurope may not show drop-off charges until the final quote. Sometimes autoeurope is cheaper, sometimes not.

Laura makes a good point. It can take a fairly long time to get your car. If it's a small branch (like Colmar), there may only be one agent and if there are one or two customers ahead of you . . . . ditto when you return the car, except at the airport where it's usually assembly-line efficiency. Or the car may not be ready (being cleaned) or may be off-site.

Thanks for the advice everyone! We decided on the train. We didn't really want to be in the car for 6-7 hours and then be tired when we get to Bonnieux. At least on the train we can have a nap or get up and walk around if getting tired of sitting. Yes, it's a bit of a pain to have to do the two car rentals, but I think this is what will work for us.

I appreciatie the help and suggestions! I'm sure I'll have more questions as I continue to plan, so thank you again in advance!