France to Switzerland

Paris to Lauterbrunnen is a 5,6 to 6+ hour journey. The train does not go to Colmar but you could disembark at Mulhouse-Ville and transfer to a direct train to Colmar. That journey is 19-37 minutes. You would reverse the process to continue to Lauterbrunnen. It is up to you if you wish to see Colmar and make this detour. It is certainly doable, but you would want to make sure you can leave your luggage at one of the stations.

1. Lauterbrunnen to Geneva Airport is around 3.5 hours. You can depart Lauterbrunnen at 7:32 am and be at the airport at 11:11, not quite a full three hours (the recommended amount) before your international flight.
   

Personally, I would prefer to reduce the stress and stay closer to Geneva before an international flight. We did that in similar circumstances a few years back after spending a few days in Gstaad to watch tennis. We took an afternoon train on the lovely Golden Pass route to Montreux and then continued to Morges, a small village on the lake, for our last night in Switzerland. It was an easy and unstressful 30-minute ( or so) ride to the airport in the morning for our flight.

I agree with Lola. I would stress that it would be a lot of effort to get to Colmar and that will cut into your time for Lauterbrunnen. Colmar is lovely, though far from my favorite of the Alsace villages. Lauterbrunnen is spectacular and I think once you see if you will want every minute you have scheduled for it and more! I would also play it safe with your flight out of Geneva. I would stay close to Geneva and not in Geneva, which is very expensive and not all that great. There are lots of nicer towns on Lake Geneva than Geneva.

If you are booking or organizing your trip yourself you should look at familiarize yourself with train schedules or services and distances between cities. That will answer a lot of your questions related to what is feasible based on the travel times on a train that you don't mind versus what others may not like. Google maps works really well for this as they seem to have the train schedule data for major railways around the world.

Once you get an idea of how far cities are from each other, to see train fares or buy tickets, you should either use trainline.eu which consolidates multiple national rail lines with out marking up the ticket prices or book directly with the national rail line. You can find links to European national rail services on this site https://www.seat61.com/

Thank you so much for all the feedback...it's helpful to hear the different perspectives. Is there a town other than Colmar that would make more sense to stop at on the way? We are wanting to experience a quaint town like Colmar. Any recommendations for towns to stay in on Lake Geneva?

Lauterbrunnen is a cute little town, as is Gimmelwald, Murren, and Wengen. Are you driving or using a train? I still think you are better off just getting to Lauterbrunnen, but I would look at a map of the train route, or highway to see towns on the way. I initially I thought of Annency, which is on my bucket list, but looking at a map, Annency is south of Geneva. I've done a lot of googling (or in my case BING) and also on pinterest searching for "cute/quaint/medieval" towns in France. I then look at a map to see if any are in the general location of where I am traveling. It has worked out quite well for me, and I haven't been disappointed.

Taking a train! The challenge is not packing in too much, but it's tempting to try and fit multiple places in while you're over there.

For Lake Geneva, look at Lausanne, Montreux, or Vevey, in order from largest to smallest. All of them have train service right to the Geneva airport.

If you only have three days for Paris and three days for Lauterbrunnen, I agree that it's not worth a detour to see Colmar - or anywhere else. Just spend your time in Paris and the Berner Oberland - two wonderful places. I also agree that if you want to "experience a quaint town," you will get all you need right in the Lauterbrunnen area; no need to make a long detour just for that.

To find train schedules for almost all of Europe, you can use the Bahn (German Rail) website http://reiseauskunft.bahn.de/bin/query.exe/en, following Rick's tutorial: http://www.ricksteves.com/travel-tips/transportation/trains/online-schedules. Note that this only has prices for trains that start or end in Germany.

To find Swiss transit (not just trains, but buses, boats, and even walking directions), use Swiss Rail: https://www.sbb.ch/en/home.html. For instance, if you want to go from your hotel in Lauterbrunnen to a hotel in Vevey, don't input "Lauterbrunnen to Vevey"; instead, put in the exact hotel addresses, and you'll get door-to-door directions!

For French trains, you can use https://en.oui.sncf/en/. I have not had problems with this, but some have, so if you're just looking for schedules, it's easier to use the German or Swiss rail sites. To buy tickets, some find it easier to use Trainline https://www.trainline.eu/, but note that they do not work with Swiss Rail.

I'd definitely stay somewhere near Geneva the night before. The last couple of times we flew out of Geneva we stayed in Segny, France, about a 15 minute drive from the airport. We stayed at http://www.labonneaubergesegny.com/. It's a great place, and across the street is a fantastic restaurant (Chez Arno), as well as a great cheese shop and a bakery. But there really is nothing to see right in town, and as a practical matter you need a car. Others above have mentioned places that have trains right to the airport. There's always Geneva itself, but I wouldn't recommend it. The first time we flew out of Geneva we stayed in the city, and I have no plans to go back.