trip planning -- how do you decide how many days for a set of smaller cities?

It's a good question, and my advice would be to do as much reading and research as you can, and ask lots of questions on forums such as this. A general guide would be to stay a single night if you are short of time, 2 nights if you are more relaxed for time and 3 nights if the area has considerable attractions. Then start juggling, perhaps, to fit it all in. For you, in 2 weeks, from Paris ...
Rouen (2)
Honfleur (1)
Bayeux (3)
Mont St Michel (1)
St Malo (1)
Brest (2)
Quimper (1)
Nantes or Rennes (2)
Chartres(1)

When I was researching for my 2 weeks in Brittany I had somewhat the same situation, not much info in the general guidebooks on France. I found some good info in the Michelin Green Guide to Brittany and I would recommend that book to you as it has a good section on Rennes and at least a few pages (with city maps) on Auray and Vannes also. I also googled each town's tourism website to see what was there that looked of interest to me. I also posted questions on here about specific towns (or areas) that I was interested in and got lots of good ideas from people here about what else there was to see/do in the immediate area. Then I plotted out how much time I thought I needed in each town (area) to see everything of value to me. I enjoy the research part of trip planning so it was actually fun for me to do this.

EDIT Michelin also has a separate guide to Normandy which I used on that same trip. They were the most thorough because they concentrated on individual areas in France.

I agree that the Michelin regional guides are the best resources for smaller towns and cities. They are available in English.

Most of the Michelin guides have sample itineraries, too. Lonely Planet has the "3 days/5 days" for many places.

I have really liked the Footprint Guides series. It's a UK based publishing company. I finally looked at their website and now I know why I like them:

Today we continue the traditions of the last 90 years that have served legions of travellers so well. We believe that these help to make Footprint travel guides different. Our policy is to use authors who are genuine experts who write for independent travellers; people possessing a spirit of adventure, looking to get off the beaten track.

I have primarily used their UK and separate Scotland and Highlands books. But I think I will search out their guidebooks for other countries when I next travel.

I second Pamela's recommendation of the Footprint Guides. I have the one for Skye and the Outer Hebrides for planning my future trip to Scotland and I really like it. They have one for Brittany and a few for different areas of Normandy. They have lots of good information in a small compact size, easily carried with you.

"I'd hate to spend an hour at the marche, see the museum for 1-2 hours, have lunch, and then be walking around trying to find out what else to do in town other than drink/eat."

I think this sentence partly answers itself, as you are already mapping out some of the plans for your day. If Rough Guide or Michelin list more than one museum, are you including it in your plan for another 1-2 hours? What do those books say about the local cathedral, the town square, the popular park area, the famous jam factory? If they don't list more specific tourist attractions, then there probably aren't any more must-sees. To find any limited-time special events, the Tourist Office is usually a good resource.

Maybe you will run into a local football match, spend an hour watching it, and be happy with that serendipity, or maybe you are the type of football-lover who searches out the matches, etc. Or if you love photography or sketching, then you know that can fill in a fair amount of free time.

You probably can plan that you can get the feel for the historic center of a smaller city in just one day, and then extra time can vary with your style of travel or the time you have on this trip, as described in the first reply above.

All good advice above, especially the Michelin Green Guides. If a midsize town is worth stopping in, other than for lunch or overnight on a longer road trip, then it's probably worth a whole day, i.e. two nights. There's always something to do or see, even if it's not in a guidebook. But this travel style requires slowing down instead of racing through a checklist of "must sees."

How flexible is your itinerary? If you're driving, visiting cities like those you listed "off the beaten path," especially in the less traveled seasons, and willing to find accommodations the same day or a day or two ahead, you can improvise as you go along. Have a general plan and list, but be willing to move on sooner if the place doesn't offer enough to stick around, or stay a little longer if you like it a lot. Find the happy medium between (1) having every night's lodging reserved weeks ahead and (2) having to spend time searching for lodging when you first get to a town. Wifi is your friend here if you have a tablet or smartphone.

To my opinion there are two “extremes” about travelling. On one side “chasing the mustsees” what gives the pleasure of the trip, needed formost planning everything in detail, without any room for flexibility and on the other side the pleasure of “just being there” needing little amount of planning, so needing way more flexibility and visiting the sites are more a bonus. But some planning remains needed to my opinion to give direction to your trip.

It remains a personal preference where to operate on the scale between these extremes but looking back to my own trip to France last week I become more and more aware that “just being there” is what gives me the most pleasure, actually not the “mustsees”. And that has influence how planning and certainly experiencing the trip.

What I mean with “just being there” is that you enjoy the destination anyway and it takes away the pressure that the trip is focused on just chasing places of interest. So you need a less strict planning as time becomes a less dominant factor. It´s very hard to say how long you will enjoy a place beforehand. If an area is of interest, get with the help of the mentioned guides / internet etc. enough information what to expect and base yourself there at a strategic place. From there explore the area and visit the town, village or place as long as it can capture your interest and after that, if you like go to the next place, and so on. So at home collect information about what to expect and make a list including places you want (not “must” though) to see, but with enough room for other places, interests, activities etc. Visit the places of the highest interest as long you can enjoy it and see on the spot how much time / room there is for other things. Likely the TI or your hotel / B&B can give tips about “hidden gems” , so expect there is room for that too.

The more of the beaten path to my opinion the harder it gets to plan, so the more flexibility is needed. The lesser strict the planning is the more you will slow down and the more enjoyable, involvable a place become and to my opinion the more you will get. It requires a different approach / mindset and I think it makes the question how much time to spend at places less urgent. So as you can see I don´t / can´t give exact times to spend in places, but more the way to approach your question in a different hopefully more rewarding way.

The packing/unpacking gets to is, so we rarely stay less than 2 days anywhere. We find something in an area and then do day trips. We picked one based on cooking classes and ended up in Tavel, a small town outside of Avignon. It was a B&B a that did dinners as well and then we did day trips in the area.

I've been reading the posts here and finally decided to see if I can help. When we decide where we want to go we sit down with a calendar, a pad of lined paper, and a couple of guidebooks.. At the top is the date we leave home and at the bottom is the date we return home.

Then we decide where we want to go on that particular trip. Usually the first two nights are going are at the Schiphol airport, and so are the last two nights. So that's four nights.

Then we begin filling in the places we want to visit. There are usually at least three nights at each one, sometimes two. With the calendar and pad we fill in the individual towns or cities. Our trips are at least thirty days and some six weeks so we have a little wiggle room as we fill in.

On our last trip we repeated part of a previous one so that was easy. Once the days are all filled in and we know where we will be every night my wife booked our hotels along the way with an online booking service. There was no error. Before this trip we have gone on the fly and found lodging as we arrived at each town. It was nice this time knowing each of the hotels were expecting us.

That's really all there is to it. In two hours you can have the planning done and maybe another hour or two to book the hotels.

I haven't done it for the cities you are considering, but when we plan a trip, I'll often look at how much time guided group tours spend in various places and what they see/do at each location (such as visit sites and/or take a cooking class, etc.) Then, I'll also enter the names of individual cities in TripAdvisor. There will be photos posted by various individuals, and there will also be an icon for "attractions." Take a look at that list of attractions, and you can click on any one of them to learn more and also see photos (posted by various people).

By looking at general photos posted of villages/cities, you will get a potential feel for what might appeal to you. If you like the idea of a cooking class, then you can enter into Trip Advisor "cooking class Rennes" as an example to see if there are any offerings, etc. Ditto for hot air ballooning or wine tasting, etc. And, you can read the reviews others have posted about each village, activity or site.

Oftentimes, you'll get ideas for things that group tours don't offer or ideas for things to do that you might not have ever dreamed of doing. If you want a guide for any area, just enter "private guide" and the town's name....then usually a guide's web site would have a sampling of activities or sights to see.

And, as other have said, sometimes it's just fun to have a day or two to 'wander'.......driving along (or having a driver/guide take you) and pop from village to village, just exploring and taking in 'life in France.'

To answer the original question, you remember that 2 nights = 1 full day of sight-seeing. 1 night = less than a full day to do and see the things you paid all that money to see.

I like the above replies, so I'll just add that no matter how much research I do, inevitably I end up with too much time allotted to some places and too little time at others. There's simply no way to know how you will feel about a place until you go; the highly touted can be a bust, and what other people find "meh" or even "bleh" can be great for you. I like Rick's statement that each trip would better if you could take it twice, with the first time being the rehearsal where you iron out the kinks, and the second time being the real thing where you get everything right. Of course, that's not possible - so I try to accept that despite all my planning, there will be some "mistakes," and a common one is how long to spend in each place.

One thing I do look for is "escape options" in the form of day trips. If a place has a lot of these, I worry less about how many nights I'm spending there, as I can easily leave if I don't like it. If a place has few recommended day trips, I'm inclined to cut down my time there, just in case.