With 5 adults to one baby then from our experience (initially 3 under 7yrs) the train would be the clear winner for most of those journeys mentioned.
If 4 adults then I'd have suggested possibly rethinking itinerary slightly and driving some while setting GPS to avoid tolls - that way you find some great villages, sights, food. % adults and baby = train.
Some extra info (&/or reinforcement) that you have probably absorbed from elsewhere but just in case:
The longer the train journey the more risk that every seat will become reserved at some time along the route. For example, one year we travelled on NY day from Munich to Austria. We traveled 2nd class, no reserved seats. The train was so full by the 3rd stop that bags were piled 3 high in the corridors, there was not one seat in the 28 carriages NOT reserved, so we got to stand, and move out of the way every time someone wanted to go to the toilet/dining car for the 2 hour journey.
June 2017 Munich/Paris saw first leg having our own 6 person compartment for the entire leg, the 2nd saw about 8 empty 1st class seats and the rest reserved from ICE start. At first stop, more people got on with 1st tickets than empty seats and 4 or 5 had bought them at that station so no reserved seating. 4 had to stand for the next 90 minutes until one family got off. Then They had to get up at next stop as people got on with those seats reserved....
Enough said.
If 4 adults then I'd have suggested possibly rethinking itinerary slightly and driving some while setting GPS to avoid tolls - that way you find some great villages, sights, food. % adults and baby = train.
Some extra info (&/or reinforcement) that you have probably absorbed from elsewhere but just in case:
- You can book trains to/from Germany as well as within Germany using the DBahn site.
- Create an account with DBahn asap and then it saves your searches to make life easier ongoing, also you get sent special offers (Eur 29 to other European capitals for example).
- 13 weeks to the day is the max in advance you can book - so try some dummy bookings on same day of week a few months earlier (if needs be) to see what the availability/connections are like.
- Paying an extra Eur10 each for Munich/Paris to get 1st class recently meant we not only had reserved seating in our own compartment (so no baggage wars) BUT even better we got access to the 1st class lounge at Munich Hauptbahnhof. The air temp was 33 degrees, not the slightest breeze and in the lounge it was 21. Comfortable armchairs, or window couches/benches with waitress service. barista coffees, teas we had never heard of, steins of beer, made-to-order sandwiches (6 to 8 varieties I think it was), soups, entrees, mains, and DESERTS. Best Eur 10 we've ever spent for a comfortable 2 hour stay (traffic was light, hire car return took 90 seconds & was 2 minute walk from the station). In winter it is warm - the station is -6 to zero!
- Factoring cost of getting to/from airports as well as time saving needs to be done.
- Nearly every train has a dining car or two - so can provide a diversion (sanctuary) if needed.
- Only way to see the real Germany/Czech Republic etc.
- To/from airport in Prague in car or taxi was Eur 50 or so.
- Sometimes it is better to book a journey as two returns rather than one (better prices and times). For example breaking a trip from Frankfurt/Innsbruck rtn to Frankfurt/Rosenheim and Rosenheim/Innsbruck saved Eur 95 for the five of us and was 45 minutes faster than booking it as one. The algorithm does not seem to like breaking an ICE journey other than at its end.
The longer the train journey the more risk that every seat will become reserved at some time along the route. For example, one year we travelled on NY day from Munich to Austria. We traveled 2nd class, no reserved seats. The train was so full by the 3rd stop that bags were piled 3 high in the corridors, there was not one seat in the 28 carriages NOT reserved, so we got to stand, and move out of the way every time someone wanted to go to the toilet/dining car for the 2 hour journey.
June 2017 Munich/Paris saw first leg having our own 6 person compartment for the entire leg, the 2nd saw about 8 empty 1st class seats and the rest reserved from ICE start. At first stop, more people got on with 1st tickets than empty seats and 4 or 5 had bought them at that station so no reserved seating. 4 had to stand for the next 90 minutes until one family got off. Then They had to get up at next stop as people got on with those seats reserved....
Enough said.