Question about quick airline stops

Which airlines and which airports?

IcelandAir is not a concern. Their inbound flights from east and west meet at Keflavik with the idea that they are a hub and people will be ongoing. They make it happen even if delays are involved. Their connection times are legit. Also it is a small airport.

Some examples:
Iceland air from ORD - CDG stops for 1 hr at KEF
Iceland air from FCO - ORD stops for 45 mins at KEF

Aer Lingus from BOS - CDG stops for 1hr 15 min at DUB

Azores Airlines from JFK - CDG stops for 45 mins at PDL

I haven't been to Reykjavik recently (I know it is highly efficient), but my policy for other European airports is to be sure my transfer time is at least one hour longer than the minimum I see for other connections at the same airport. You don't necessarily have to be that conservative, but it makes me worry less in the time leading up to the trip. Although I prefer later departure times (in hopes of actually napping just a bit on the plane and avoiding such a long, miserable arrival day in Europe), arriving at the transfer point earlier in the day makes it easier to recover if you do miss the connection, because there will be more flights going to your ultimate destination. The airline will have to get you there--assuming you are traveling on a single ticket--but it can't get you there until there's a flight with empty seats.

I've found Amsterdam and Munich to be manageable transfer points. I've flown in and/or out of Heathrow and Charles de Gaulle but have avoided them as transfer points on the basis of comments on this forum.

As noted, the Icelandair transfers in Reykjavik are efficient and timed decently by the airline - a one hour connection is common. You could consider an Iceland stopover if you fly through (better on the way back, less jet lag).

You are lucky that MSP has more than one direct Europe flight - Amsterdam, London Heathrow, and Paris on Delta/KLM and Frankfurt on Condor. I personally prefer the convenience of flying from my home airport and not trying to get to another US airport to catch an international flight (time is money). I'd set Google Flight alerts on searches for more direct routes (including the one to Paris) for price tracking. It's possible prices will go down over the next couple of months, though the Olympics in Paris are going to inflate prices and clog up capacity all summer, even in July.

Icelandair and Kelfavik airport are masters at the short changeover. They specialize in it. You will exit your plane, be ushered through immigration, and then put on your next flight. It's very simple and the distances aren't far.

With Dublin and Aer Lingus, you won't have to go through immigration in Dublin, just go from one flight to another.

Dublin even put out a connections guide:

https://www.dublinairport.com/flight-information/connections/connection-guide

Remember, however, if you fly Aer Lingus back to the US and change in Dublin, you will go through US immigration and customs at Dublin airport so you will need extra time.

I can't help you with the Azores flights.

Thanks for all the insights! Very helpful.

One of the reasons for considering a dif. airport was to get an economy flight for a shorter flight and then 'hopefully' upgrade to a more legroom seat for the longer/overseas flight. I'm short and I have no issues with flying economy for long flights. My husband is concerned about not having the space and would like to consider other options based on comfort. It has been a while since I have flown to Europe and unsure whether seat space is an issue.

You may want to consider this general advice regarding tight connections -
https://www.travelandleisure.com/rick-steves-tips-to-avoid-common-travel-issues-7367914

European airlines like to offer short connections. It is a very competitive market, and they are competing with other airlines that offer direct flights.

But they will not offer unreliable connections. After all, having to rebook you, and feed and lodge you if you cannot be sent on your way promptly, and paying compensation on top of that is not good for the bottom line.

So the incentive to make this work is there. And in my experience it does. Before the pandemic I flew almost weekly, and often connected through either FRA or MUC. And even in FRA a connection of only an hour (or even less sometimes) would always work.

So I would not worry to much about that. These short connections are normal.

One of the reasons for considering a dif. airport was to get an economy flight for a shorter flight and then 'hopefully' upgrade to a more legroom seat for the longer/overseas flight.

If Business or Premium Economy Class is important to your husband, then find the best price on for those classes and book them. Upgrades by the airlines are not at all what they used to be and not worth the effort.

If you want some sleep on the flight to Europe, I recommend against the Azores flight: it cuts the flight in half in the middle of the night (for you). The fares look incredibly low, though. I'm seeing $200 one way flights in December!
Flights through Iceland have a similar issue, but an Iceland stopover could be fun.

You need to be aware that irregular operations can happen on any airline, anytime, anywhere. There are no guarantees that any amount of time will be enough for every connection.

The result is that you need to plan with the idea that something “could” happen. This means no “must do” arrangements on arrival day. Examples would be timed reservations at a bucket list location or embarking on a tour or cruise.

The good news is that most connections are made and most people together to their destinations as planned.

PS It is possible to pay for extra legroom seats on Icelandair after you buy your ticket. You do this as part of a seat selection process and well worth it to me.

We flew MSP/OSLO on Icelandair in September, and the short transfer time wasn't an issue. It was really nice to get off the plane after six hours and stretch before continuing onto Norway. Their early morning check-in at Humphrey was a bit disorganized, and the onboard entertainment didn't work on leg 2 of our first day. The price was good, the seats were comfortable enough, and our luggage didn't get lost, so that was a win for me.

We've only flown Aer Lingus just prior to Covid, and it was a good experience.

In 2022 we flew RT non-stop MSP to Paris on a Delta ticket and premium select seats to Paris. I loved those seats! I always look at Delta first.