Flying out of Colmar

If Basel is cheapest then there's no question really, as it's also very close and doesn't have any critical issues.

Colmar doesn't have an airport. The nearest are Basel and Strasbourg.

• Basel only has one seasonal North American flight a week, to Montréal. See list of destinations here: https://en.wikipedia.org/wiki/EuroAirport_Basel_Mulhouse_Freiburg#Passenger
• Strasbourg has none. See list here: https://en.wikipedia.org/wiki/Strasbourg_Airport#Airlines_and_destinations
• Zürich has direct flights to Chicago by Swiss: https://en.wikipedia.org/wiki/Zurich_Airport#Airlines_and_destinations

So I would go for Zürich. Basel requires changing planes, and Paris involves doubling back through city centre, and would take longer. You can get to Zürich airport direct by 2 trains (Colmar - Basel and Basel - Zürich Flughafen/airport).

P.S., when my colleagues are trying to save money they fly out of Basel, changing London or Amsterdam. Both are cheap due to lots of competing airlines. If the company is paying, they fly out of Zürich with a direct flight, less stress, less time.

If the closest airport has the best prices why would you want to look further away?

Thank you for your reply and especially Chris, thank you taking time to answer my question. I'll look into the price difference as we're paying out of pocket.

I would change my itinerary to start and end in major cities with international airports. Cost and availability will probably favor Paris over Zurich. I tend to try for non-stop flights and avoid connections if possible.

Richard,
I thought of that...we're doing London-Paris-Alsace...
We don't care which order we go but given the locations of these 3, and if I want least amount of travel time, then it's as is or just the reverse. Do you have any suggestions? I'm very open to advice!
Thanks again.

Well the other thing to consider is upon arrival in Paris (from London via Eurostar?), you could change train stations from Gare du Nord to Gare de l’Est (they are right next to each other), and go directly to Colmar instead of spending your time in Paris then.

After you’ve seen Colmar, take the train back to Paris for your last few days and your visit there, and then fly back home out of Paris.

Start in Paris and then train to Colmar. Fly Basil to London which when booked in advance could be cheaper than the Eurostar. Fly home from London. Or do the reverse, it will depend on flight availability.

And what happened to Rome, Lisbon and Portugal?

Richard and Kim, thank you for the suggestions. I'll look into flights and train options for what you both suggested.
This trip is for my family in June and trip to Portugal is for my mom's 70th bday in March. Portugal trip is almost all set, thanks to all the advice from this forum!